Let’s review a project that incorporates all of these principles:

The aim of the Pi Box was to produce an affordable case for an affordable computer, and to get it in users’ hands quickly. Around the same time I’d read something on design for manufacturability, and this had me ruminating on how cases and kits are produced…

We already had a really nice case design for the BeagleBone: our Bone Box (shown below). But the Pi threw us a couple of curves. First: it’s really inexpensive. We couldn’t see justifying a $20 case for a $35 board. It had to be under half the board cost. Second: early versions of the Raspberry Pi had no mounting holes, so we couldn’t rely on the usual screws and standoffs for holding a board in place.

The solutions to both problems are actually related. Much of the expense of an item like this isn’t in the materials, but the manpower. Kitting — counting, collecting and packaging all the separate components that make up a kit — takes time. If we could reduce the scope of this extra hardware-counting step, we could produce a more affordable item than the Bone Box. And then, without any mounting holes on the Pi, we needed to do something differently anyway…there was no point to stand-offs here. So, partly for these reasons, and partly as a matter of stubbornness, it became a personal challenge — my one more thing — to develop something requiring no hardware at all. Six laser-cut acrylic pieces come out of the machine and go in a baggie, and the kit’s done. There’s one small piece that the customer snaps off; this wasn’t fully cut as a separate piece, as fishing out these tiny parts from the laser bed would take more time.

This “simple” box required 23 iterations to get just right. I’d originally tried a number of slotted designs, which mostly just fell apart. The idea for the “Dragon Claws,” exploiting the slight flexibility of the acrylic, didn’t come along until about a third of the way through. My favorite part is the little “grippy marks” on the underside of the claws. These aren’t the least bit functionally necessary, but their appearance gives a subtle hint as to how it operates: press here.

Most of the prototypes were in funny colors. But this was just the scrap feeder stock on hand…it was already known from the beginning this would be produced in clear acrylic, as it’s the most affordable color. But every bit as important: the Raspberry Pi was a phenomenon and I knew people would be eager to show off the little wonder-puter inside. Opaque or even tinted acrylic would hide that. I think this has been a reason for this case’s continued popularity, even after affordable injection-molded cases have come along.

Another popular feature, that the case still holds together with the top off — leaving room for accessories like our LCD Pi Plate — was a fortunate design fluke. I have to admit that wasn’t specifically planned that way…sorry to disappoint. :)