This is a case that allows you to mount a Raspberry Pi 3 to an Ender 3 or Anycubic Kobra (and other 3D printers that have 4040 aluminum extrusion).
Tolarances aren't perfect so you may need to edit the f3d file or file down the rails after printing. Print with supports under the top rail. To attach, just slide it down the extrusion and mount wherever (I put mine behind the LCD screen).
Rails were taken from @AlexKrush_390605's RPi 4 mount model with 1mm tolerance. Everything else was taken from @Stamos's RPi 3 case model - use the covers found here.
The author remixed this model.
Rails for 4040 aluminum extrusion used on Ender 3 and Anycubic Kobra printer models