I needed a case and holder for my Octoprint server. I couldn't find any solutions for the Raspberry Pi 3A+, so I had to design something myself from scratch. The case and the holder are designed to snap together and fit snugly, so no screws or tools are necessary for assembly or disassembly. However, the case might fit just a little too tight to the holder, so you might have to use a flathead screwdriver to bend open the mechanism to remove it. The holder hangs securely over the top of the UM2 chassis, and is easy to remove. There are two cable guides to guide the camera cable around the inside edge of the chassis and behind the belts and rods. If you want to place it between the arms of the case holder (like I have), use cam_cable_holder_2, otherwise use cam_cable_holder_1.

As a camera holder, i use one I found at thingiverse.com (https://www.thingiverse.com/thing:3910671). To use this, you will need a longer camera cable, like this one (https://www.aliexpress.com/item/32895011936.html) available from aliexpress.com. I use a 50 cm cable, and have tucked about 20 cm down between the case and the outside of the UM2 chassis. So a 30 cm cable will probably be long enough. As for mounting the camera holder inside the chassis, I used Tesa Powerstrips (https://www.tesa.com/en/consumer/mounting-hanging-sms/adhesive-strip-powerstrips), which is an easily removable double sided tape. It doesn't look very pretty from inside the printer, but I used them while searching for the best position for the camera, and decided to just keep them (because who sticks their head inside the UM2 to have a peek? ;) You could also use 3m Command strips (like these - https://www.command.com/3M/en_US/command/products/~/Command-Small-Refill-Strips/?N=5924736+3294529207+3294736527).

Another camera holder that works very nicely is also from thingiverse (https://www.thingiverse.com/thing:3816440). With this one, the camera sits on the top, near a corner. With this holder, you can use the stock camera cable that comes with raspberry pi cameras (15 cm). However, I tend to prefer the view from inside the chassis, so I use the camera holder mentioned above.

I use a 150-degree wide angle camera, obtained from aliexpress (https://www.aliexpress.com/item/32726563700.html). The field of view on stock Raspberry Pi cameras are too narrow for my taste, but your mileage may vary. This camera can be used for both the inside and top mounting solutions described above.

I have included the FreeCad files so you can more easily improve on the design or make your own adaptations and remix. This is my first design, and I'm pretty sure I've made some rookie mistakes in the design or in how I used FreeCad, so please go easy on me :-)