My Prusa SL1 resin printer is in the basement and I don't want to walk down every hour to check if the print still sticks to the buildplate.
That's why I made this small camera to observe it.

What you need:

Raspberry Pi Zero W with micro SD card
Kuman Camera Module with ribbon cable
4 strong Magnets 20mm x 2mm
Micro USB Power cable (90° bent)
Electrical tape (the sticky rubber kind of tape)
Super glue and Hot glue
Assemble:
After printing the two cases you can glue in the Magnets with super glue.
Be sure that the Magnets are facing the right way and attract each other!
I also glued the two circuit boards and the two lids to their cases with a drop of hot glue.

Hardware:
You can stick the Camera and the Pi to the orange glass without damaging the printer (no holes, screws etc. needed).
The Camera is on the inside and the Pi on the outside of the orange glass.
The two shells will stick to each other by using 4 Magnets.
To increase the friction on the orange glass I used a bit of Electrical tape and stuck it on the glass-facing sides of the two shells.
The ribbon cable connecting the Pi with the Camera is very thin and will keep the seal of the printer.
You can adjust the focus of the camera by rotating the lens on the front.

Software:
I installed Octoprint on the Raspberry Pi Zero W.
It is not connected to the printer but it provides an easy WiFi access and the video stream of the camera.
https://octoprint.org/