Inspired by xiphmont's implementation, I created my own files for the enclosure and pi3a+ frame for this update. Please follow xiphmont's guide to install the pi3a+ and perform the upgrade. The installation was flawless for me with the included octoprint image. Xiphmont's original cover file is included for completeness.

I had some issues printing the pi3a+ spacer frame and had to simplify it. The many holes for the keepouts on the Einsy board had a problem sticking to the textured sheet. I also optimized wall thicknesses and features to work well with the Prusa printer part settings.

The pi3a+ frame and Einsy housing has routing support for a 16mm wide FFC cable to connect a pi camera to the on-board connector. The frame also has a bit of clearance for the hex key to access the top mounting screw.

I have this upgrade implemented on two MK3S+ printers and the pi's with connected camera run without any issues. A world of difference from the ZeroW.

An installation point of note:

Slightly bend the FFC cable after plugging into the pi, away from the HDMI connector, about 20° and no more. You will crack traces if you bend it at 90°. The slight bend will help it to naturally seat in the right direction during install. There's a ramp in the frame that will also guide it but it needs a bit of help.