No need to stick or damage your 3D printer. Yes, Ultimakers have their own camera, but if you are used to have full control over your Raspberry Pi and Pi Cam (especially for distant monitoring outside the local network), there is a choice for you now… ;)
BOM:
1) Raspberry Pi Zero W;
2) Pi Camera;
3) 2 pairs of 20mm M3 screws and nuts;
4) all of these 3D printed parts;
5) memory card with installed surveillance platform of your choice (tip: OctoPrint works fine, even if you use only camera part. ;) )
Technical
Print all of it it with standard 0.4mm nozzle and 0.2mm layers. Only „Pi_Zero_case_bottom.stl“ needs some supports.
There are no great tolerances, because I wanted to have everything easy snap fitting. So if your 3D printer is callibrated different way, be ready for a little grinding. Also, the difference between the thickness of left and right side case cover of my UM3 is 0.5mm, so maybe yours is also a bit different. ;)