This is a tray I designed to hold the Raspberry Pi 3B+ case from Canakit.
You just set the case into the tray and there is enough clearance for all the I/O allowed by the case. Holds the case place well but remains easy enough to remove if necessary and mounts very strongly to the printer's rail. It's made to work for the Ender 3 v2, but assuming the other Ender 3 versions use the same rails it should work for them too. Designed to use the left side rail, but can be mirrored in the slicer or modeling software very easily to be used on the right side rail (behind the screen I would assume).
Print instructions:
Installation instructions:
The author marked this model as their own original creation.