2 part insert for IKEA Helmer drawer. Just about fits on a MK3 bed. And I mean just about, smaller beds need not apply ;) As for the license, the original model does not specify one. Since I have to pick one on printables, I went with CC-A-SA, but this is not binding, since I am not the creator and as such have no power to define it.

If it does not fit your printer, someone on printables has made a version in four pieces: https://www.printables.com/model/361855-gridfinity-baseplate-for-ikea-helmer

Description by author:

These 2 parts combine to form a Gridfinity Baseplate for an IKEA Helmer Drawer. I included some 1.75mm holes where you can insert short lengths of filament to help line things up. There's also some 6mm x 3mm magnet holes on the underside if that's your thing.