The clasp was modified for utility blades that do not have the set of 4 holes in them. The holder loop was also removed. The modified f3d file is included for further remixing. Be careful with this tool - use at your own risk!

Updates:

1. I have corrected the Fastener STL file for the proper thread direction (my error in previous upload).
2. You may want to thicken the clasp slightly so the top sits slightly proud of the holder body to get a stronger clamp down force onto the clasp and blade.