Simple adapter from 3/8" to 1/4" tripod threads. I designed this to test the accuracy of my printer and strength of the printed part. Works great on Prusa i3 MK3S with PETG -- I might just use it!
Please test the strength of the part and make your own decision before using it for anything precious. No warranty expressed or implied!
Fusion 360 design file included with some named parameters.