I was assigned the task of creating a case for the product. Having no experience with 3D printing nor Blender made the task seem quite daunting, especially considering the time limits our project had.
I referred to classmate and Blender expert Antti Eloranta for advice, and he helped me tremendously early on with coming to grips both with Blender, and later with 3D printing. With his help, we created the first prototype in Blender, fusing together two cases found from Thingiverse. Our first attempts at printing it were failures, however. The Print-Rite 3D printer (nicknamed “Donald”) we have at school wasn’t something either of us had used before, but it was the only one with a bed large enough to fit the design. For some reason, we were only able to print a mess of stringy plastic that only barely represented our design.
After a bit of frustration we had help from our teacher Heikki Hietala, who teaches both Blender and 3D printing at our school. He remarked that the Print-Rite is a bit different in what it likes as settings to print correctly, so we tweaked our printing settings according to his advice. Namely, temperature for the extruder was bumped to 245 degrees celsius, and the bed to 110 degrees. The next time we attempted printing, everything came out correctly, and we had a functional bottom part of the case.
I then designed the top part of the case, and attempted to print that. This time, the print failed with the filament getting tangled. So lesson learned again; I cut the filament to get rid of any kinks, reinserted it, and the next attempt was successful.
When I put the case together however, it cracked in two places – it wasn’t quite strong enough. As I also realized that I didn’t like the green color of the ABS plastic I was printing with, I decided to change the filament to white, and make some test prints to try out the different settings of the printer. I ended up choosing 40% rectilinear infill, 0.2mm layer height and 0.3mm for the first layer, slowing down the speed of printing a little when printing the smallest layers (to prevent melting), and also using a 3mm wide brim (for stability). For the 3D models, I ended doing some modifications; the logo was enlargened, and some parts – especially the bottom of the Arduino part – were thickened. As the white filament was also ABS plastic, the temperature settings remained the same.
The final case came out very nicely, I only did some sanding to make it more presentable.
After the case was done, I realized that I had made a rather big mistake. While the Raspberry Pi have similar dimensions, they have different connectors, and we had ended up deciding to use the newer Pi 2 Model B in our project. Thus, the Pi 2 did not fit the case.
However, this time around, I was already a lot faster and more experienced in Blender, and was able to finish a design for a new case in only a few days. Again, I used two cases found from Thingiverse as the base, but modified them to suit our needs better. I also created a little case for the PIR sensor we used, and made it so that you can attach it either to the top of the case, or further away using a separate bottom part. Please ignore the support structure pillars built into the model, they are just for printing.
In the end, after a lot of sanding and some nail polish remover, this is what the end result looks like: