Loved the original sanding block, but I wanted to use threaded inserts instead. Strength is likely less than nut-based design, but as the great philosopher said, “When push comes to shove you gotta do what you love; even if it's not a good idea.”

Created STLs for M4 insert, 5mm diameter, 5mm height. M4 16 worked just fine for me.

Also bored out the locking piece to fit M4 clearance sizes.

OpenSCAD file included to parametrically change sizes or tolerances. I make precisely zero promises about any size other than the exact M4 inserts I was using. Original STLs from Zeraldo are used for the OpenSCAD file and are not included in this package. The included STLs may work, but I encourage you to grab the originals for the lowest chance of artifacts from load/modify/save errors.

Be sure to export both part 0 (body) and part 1 (lock) from OpenSCAD!

Let me know if there are any issues with the insert version, and thanks to Zeraldo for the wonderful tool!