DeWalt XRP 18v Battery Holder for Multiboard
This is a modification of https://www.thingiverse.com/thing:5828863 with the base modified to fit the 12.5mm pitch of Multiboard. (https://www.multiboard.io/)
Supports are optional, but will give you a more crisp part. I've printed several without bothering with supports and it comes out okay. Your mileage may vary.
This new base fits Multiboard and the holes fit a small-thread 13mm bolt like this one: https://thangs.com/designer/Multiboard/3d-model/13%2520mm%2520Small%2520Thread%252C%2520Plain%2520Head%252C%2520Bolt-974409