I couldn't find a battery cover for my older model Mitutoyo Digimatic 500-322 digital calipers, so I made one. This snaps in pretty securely, but if you still have the tiny screw that held the original in place, you should be able to drill out the nub in this model.
This is a replacement for Mitutoyo part number 145171 (old version)
This thing was made with Tinkercad. Edit it online https://www.tinkercad.com/things/3N7BYF2rc0q
This model was designed for a 0.1mm layer height. I have not tried printing it at any other resolutions. I printed using supports for the two tabs only, but supports may not be necessary.