Just one STL file (and one screw.. plus four if you want to print and screw a cover on your pi) is all you need to mount your raspberry pi (4B) and camera (v2/2.1) to your ender 3 (and/or ender 3 pro)!

You don't even need to print a back for the camera mount because the tension from the (regular length) cable keeps it nice and snug! The camera has been painstakingly oriented to keep the extruder in the center top of the frame. No need to adjust a thing!

If you want to print a top cover for your raspberry pi 4B, pick one of mkellsy's: https://www.thingiverse.com/thing:3793664

The camera mount came from Codemonkey1973: https://www.thingiverse.com/thing:3294512

You can also string a USB light (or two) through the triangle, for night printing. Like this one: https://smile.amazon.com/gp/product/B0002AKX6Y/

If you want to edit it at all (maybe you have a different raspberry pi or want to turn the camera a tiny bit?), tinker away at: https://www.tinkercad.com/things/hksT0Y2w3bg-ender-3-raspberry-pi-and-camera-mount

Any print settings you like are fine I'm sure.