Device Case Design or How to Design the Ideal Device Case

Device Case Design or How to Design the Ideal Device Case


Design rules for device cases

Device cases are made for three purposes: aesthetics, function, and protection. Designers need to balance these elements in order to create cases that add value to an expensive investment, rather than detract from it.

In many situations, device owners may want a case to meet a specific need. This will likely involve some compromise. There are, unfortunately, no universal principals for the design of device cases.

Serious Insights has developed the following rules offer basic guidance to designers of tablet cases,  phone cases, as well as computer cases. Consumers can use them as points when evaluating cases for themselves. These criteria apply only to cases for individual devices, and not to carrying cases or backpacks that offer solutions for more complex use situations.

When in balance, these rules should guide solid basic designs. When a designer, however, places more emphasis on one of the purposes (aesthetics, function or protection) the design may be become unbalanced in favor of features to support the purpose. Consumers who buy cases for those specific purposes need to recognize that they will likely make some compromises against the basic rules when choosing a case.

The design rules for device cases

The rules are broken down into positive and negative rules. Good case design is not just about implementing positive rules, but also avoiding negative rules. For any basic case, adhering to the positive rules means such a case should be considered well designed.

The list of negative rules for case design should be avoided. If they are present, they should be considered as reducing the overall value of the case, even if it adheres to all of the positive rules.

Positive rules for device case design

  • The case does not detract from the device design.
  • The case protects the device from basic damage such as small drops, scooting the device across a table, or placing it in a bag by covering corners, the back, and the front of the case. Protection may be applied via two different approaches as long as the two approaches do not increase the complexity of the overall solution (such as applying a screen protector to a phone, as well as placing it in a case).
  • The case is easy to remove.
  • The case is made of a material that is unlikely to crack after multiple removals or during normal use (a common flaw is the edges of the case “hinges” fraying or cracking after a case is bent back-and-forth a number of times during normal use).
  • The case enables unique published features of the device (such as the magnetic on-off feature of the iPad).
  • The case does not decrease the functionality of any basic device feature (it does not, for instance, cover the camera lens, obstruct buttons or reduce the quality of sound coming from the device).
  • The case should support all the basic use cases of the device.

Best design example: STM Studio for iPad Air 2

Design rules for device cases -stm

I would rate the STM Studio for iPad Air 2 as a best case design example. It works very much like the Apple iPad Smart Case, but it adds an additional, relatively non-intrusive magnetic flap that keeps the case more firmly sealed when in transport—and it also feels more secure when carrying the case. The flap does not get in the way as some flaps do, because it can be adhered to the back via magnets, keeping it out of the way, while improving the perceived safety of holding the device. This is an interesting point to consider, because this flap feature that might otherwise be considered superfluous in certain use cases, such as holding the tablet in the hand.

The STM Studio also supports typing positioning as well as content consumption simply by changing the orientation of the device once the magnetic flap as been folded back. Simple and elegant.

The clear plastic of the latest models provides visibility for the apple design and materials, while also offering a surface for customization with stickers or decals, or visibility for stickers placed on the iPad itself. In addition, the case also includes magnets on the rear of the case for holding the cover in place when it is being used as a stand. The lightness of the case, and the precision of the magnets, leaves the case easy to hold, without obstructing the camera lens. It remains “one piece” regardless of the use case.

Negative rules for device case design

  • The introduction of extra parts that are unattached and may be lost, thus reducing functionality or increasing ownership cost due to replacement. Some cases, for instance, those that are waterproof, often come with separate audio attachments that maintain protection while using wired headphones. While that may be necessary for that protection feature it adds a part that must be carried in order to support a phone feature and can be easily lost.
  • The introduction of extra material, including flaps, stands, hand straps, clasps, zipper pulls, and other elements that do not add value and can get caught on bags, in the back of airplane seats, or on clothing.
  • The use of harmful materials in manufacture or packaging.
  • The use of non-recyclable packaging.
  • Use of poor materials or bad manufacturing processes that make the case wear quickly (the use of glue, for instance, for combining material layers without any reinforcement stitching.) Poor materials include fabrics that feel extremely unnatural and create a negative feel when handling the device.

Finding balance in purpose

The purpose for the case, beyond basic protection, which is a first order purpose, requires balancing between the aesthetics of the case and the device, in addition to the function the case offers, or any extra protection. Cases that skew toward any function will never be exemplars of overall design, but if they apply the proper balance, they can remain well-designed despite favoring a purpose.


Aesthetics is about the look and feel of the case. It may be that the case is personalized, themed, or bejeweled. Aesthetics need not introduce negative design attributes or abandon positive ones. Many licensed products end up on the lower scale of protection because they are simply thin shells with logos adhered to them.

Many branded cases, for instance, are little more than minimalist shells, of inferior material, printed with a logo. While these cases may temporarily improve the perceived aesthetics of a device, they offer little protection, and are often a poor investment because they wear poorly.  Often the case with the most prominent brands are among the least well made cases available.  Other aesthetic choices that don’t add value include jewels and crystals, the use of multiple materials that don’t adhere well to each other over time, or offer less protection over all (such as an expensive leather designer sleeve that leaves the phone exposed while it is in use).

Example: The BookBook case series from Twelve South

The BookBook case series from Twelve South offers an interesting study in aesthetics. For bibliophiles, it is a very attractive option. The cases, are custom made for each iPad or iPhone model. While the iPhone cases offer a molded interior for alignment, the iPad cases are essentially two pieces, the interior being a custom fit sleeve sewn to the case on one edge, that snaps onto the rear of the case via metal snaps.

BookBook design rules for device cases

There are two areas where the design choices make for awkward functionality. The first is taking pictures. This requires unsnapping the iPad, holding it, and basically dangling the outer case while setting up the shot. This looks odd and creates balance issues for the photographer. The design can make lining up a shot difficult and provides a surface for wind or other people to jostle during the photo.

The second is the thickness of holding an iPad when folding the case cover back. Not only does it feel thick, the edges of the case extend well beyond the device, adding size to, in the case of the iPad Air 2, a slim and hand-friendly design.

The Twelve South design, however, offer superior protection from drops, as the iPad essentially floats inside of a cushioned interior that is zipped shut. The case also works very well for input and content consumption with easy positioning of the sleeve within the case. There is little fear that an iPad will be damaged during travel if it is secured in a BookBook. The case also makes an iPad blend into a shelf of books as theft deterrent.

The negatives introduced by the aesthetics and the higher-order protection features of the imitation book design are acceptable for the audience of bibliophiles who want to house their iPad in a real leather-bound book jacket. The BookBook reflects most of the positive design rules, with the exception of not detracting from the device design, because when applying the aesthetic purpose, a case will likely chose to highlight its consumers design aesthetic rather than that of the device maker. That is not a high negative, especially when the consumer of the BookBook considers its materials, basic functionality and the fact that it looks like an antique book, which is what attracted them to buying it in the first place.

[As a contrast, the imitation book and universal 7-inch “Hamlet” case I purchased at the British Library, made by bigstrawberry, isn’t overly protective as it just flips open. It relies on a single square of gel to hold the device in-place, and is made of a material that feels very unnaturally plastic. I bought it as a “bookish” souvenir, and it is just that, as it sits among my Shakespeare collection on a shelf, unused for any of my devices.]


There are a wide range of functions that people may want beyond the primary function of protection.

Additional functions may include the following:

  • Keyboard
  • Storage
  • Stylus holder
  • Hand-straps.
  • Built-in battery
  • Attachment points for auxiliary equipment like camera lenses or game controllers.

A keyboard, for instance, can serve as a positive combination when paired with a back cover for a device like an iPad. If it is light, thin and easily removed, it can be a very good choice to pair with a compatible shell. If, however, the keyboard cannot be removed from the case, and requires that it be folded back so that it adds bulk, makes it less natural to hold the device, and increases weight even when not in use, that case has not been designed well for use cases beyond typing.

Some features, like hand-straps, may be necessary for certain industrial functions. That same feature may be useful for specific consumer use cases, like hiking. This is where ownership of multiple cases may be better than finding the ideal case. A ruggedized, easily removed case with a hand-strap, may be an auxiliary accessory, because it adds unnecessary weight and bulk for every day use, but is not only appealing, but highly recommended when using a device in potentially hazardous situations.

Function: Two Logitech Paths to Design

Here are two examples of issues with function from the same manufacturer, Logitech.

ultrathin-keyboard-cover-gallery design rules for device cases

The first is one of my favorite keyboards, the Ultrathin. When this keyboard is combined with a keyboard compatible shell (made by several manufacturers) it makes an ideal cover for the iPad, and it converts into the best keyboard around. It has always been interesting that Logitech failed to combine this great keyboard with their own lightweight shell to offer the best solution around.

They do sell a number of keyboard and case combinations, and in one example, the design team went overboard, the Blok.

Logitech Blok

Unlike the Ultrathin, the Blok keyboard solution adds a bulky, square case to the elegant iPad, along with a kick-out stand that is sturdy, but made of relatively heavy material. The detachable keyboard, bound in the same material and square form factor as the case, is serviceable but less comfortable to use than the Ultrathin. While the case may offer integrated keyboard functionality, and superior protection, it is unattractive and heavy, adds an extra pieces in the stand, and it is hard to get on and off. I worried about the integrity of my power and volume buttons as I struggled to remove my iPad from the Blokl.

As a side note, Logitech also makes a flat keyboard called Keys-to-Go which works with any case that doubles as a stand (or any device propped up for easy viewing). It is not as good a as the Ultrathin, but it is functional, and its lightweight and thin profile will let it slip into any case along with a device. Keys-to-go works with any brand of tablet or phone—and with Apple TV.


Because the various standards for drop tests and water resistance don’t necessarily mean much to those buying a case for a personal device like the IP-68 ingress protection or military standard . IP-68 rated cases withstand circulating talc for 8 hours and water immersion to 6.6 ft / 2m for 1 hr  People looking for protection are likely going to give up significantly on features and aesthetics. While heavily protective cases aren’t necessarily ugly, they are certainly are not minimalist, often adding significant bulk to even the thinnest devices.

The biggest issue with very protective cases is the difficulty of removal. Another issue is that even the most protective cases are made mostly of plastic that can crack or bend after several removals. Sometimes layers of protection also detract from function, even if the function, like using a stylus, may not work as well against the protective cover for the screen as the native glass it was designed to be used on. Sometimes these cases can also be difficult to install, requiring tools, screws and other elements. One case I evaluated proved so daunting to install that the screw heads were stripped before installation was complete.

The very protective Otterbox

Otterbox Seahawks defender design rules for device cases

Many people who buy phones, especially if they have dropped their phone into water in the past, buy an Otterbox case immediately upon acquiring a new device. For this audience, protection trumps all other considerations. This is not to imply that Otterbox cases don’t attempt to balance aesthetics with protection and function, but they do skew toward protection. That makes them often thicker than other cases, which means including extra parts that can be lost, like an audio connection extender (also necessary to retain the waterproof seal). But once an Otterbox case is on a phone, it requires effort for removal. And again, that may be perfectly acceptable to those who place fear of damage over all other considerations. That said, a phone in an Otterbox case is not ideal for an accessory buyer who wants to swap out phone lenses or add on additional sensors. Otterbox, however, recognizes its own tradeoffs and has moved from simply utilitarian designs, to offer, for instance, the Symmetry Series Crystal Edition, which includes genuine Swarovski crystals on the case.

Four reasons companies design bad cases

1. The first reason for bad case design is driven by market size. With millions of devices, there are thousands of niche use cases that designers imagine and attempt to fill with a solution, as well as brands or concepts they try to attach with. In some cases, those designs need only sell to a couple of thousand consumers to break even. The number of case manufacturers and the variety of designs attests to a market capable of supporting a wide range of offers, and most of those firms make enough money across their product lines to remain viable.

2. The second reason is that there are no rules, such as the ones stated in this article, that case designer adhere to.

3. The third reason is differentiation. If the STM Studio is the best basic case on the market, why bother making another case? The answer is revenue opportunity. Device accessory manufacturers want to make money, so they create a cases that are just about like the case that gets five stars, but one made of a different material, a cheaper one, or one that is stronger. Somehow it differentiates enough to create a competitive model that also sells enough to make back its money and encourage more differentiation.

Eventually, that drive for differentiation becomes seen as a drive for innovation, and then the design teams can go off the rails, crafting designs that may be aesthetic, or protective, but aren’t overly functional, or even durable.

For the consumer, though, there is no need to buy a case with a bad design. They can use the rules outlined in this post to help evaluate their choices before they spend their money. The same goes for device case manufacturers, who may want to consider these rules when designing their cases.

4. The final reason is market access. With outsourced manufacturing and production engineering, it has become relatively inexpensive to produce a design and bring it to market. If there is a multi-billion dollar market, why not take a share, even if you know you aren’t creating the best product on the market. Given the relatively low cost of entry, a company is likely sell enough cases to be viable.

The cost of entry is even lower for those who simply distribute proposed designs from places like China. During two review cycles I received keyboards and cases that were identical to those being distributed elsewhere. In one situation it was a relatively small company selling exactly the same product as a much more established case manufacturer. Both bought products in China, and either they “licensed” the same design, or the company didn’t share that the design was already being distributed by another firm, or the design was being shared by multiple companies, that were either false fronts or separate companies, perhaps unwittingly sharing the designs.

For the consumer, though, there is no need to buy a case with a bad design. They can use the rules outlined in this post to help evaluate their choices before they spend their money. The same goes for device case manufacturers, who may want to consider these rules when designing their cases.

As always, as a learning organization, Serious Insights welcomes opinions and feedback to continuously improve the rules outlined in this post.

A campaign against environmentally bad device case design

Recycling design rules for device cases

I’m going to start reviewing products with an environmental spin. Along with the criteria stated here, it is also important to share that a product does not have well-designed, minimalist packaging. It is understandable that some products require retail packaging that makes it possible to hang a case on a hook, and also to minimize the threat of theft. But those criteria do not preclude the use of recyclable materials and minimal packaging. Evaluation cases often arrive in multiple layers of non-recyclable plastic, and each case is individually wrapped in a non-recyclable plastic bag. I hate tossing this material into the trash rather than in the recycling bin. Manufacturers need to make a commitment, as some have, to environmentally friendly packaging.

iPhone case design, iPad case design, Android case design, device case design.

See more Serious Insights hardware reviews here.

Daniel W. Rasmus

Daniel W. Rasmus, Founder and Principal Analyst of Serious Insights, is an internationally recognized speaker on the future of work and education. He is the author of several books, including Listening to the Future and Management by Design.

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