Model making often involves cutting a number of small screws to length. The cut ends need to be beveled. Ideally one would use a cone-shape lined with emery and driven by a Dremel or similar. This has never worked too well for me so I like to sand the ends against a flat Dremel sanding disk.
This means holding the screw so its end can be rotated against the sanding disk. I have several pin vises, including this homemade one...
However, all these pin vises involve operating a screw to insert and remove the screw. With lots of screws to sand that can get very tedious. The obvious solution is some sort of spring-loaded lantern-like tool that can grasp the head-end of the screw.
A clothespin came immediately to mind so I decided to do a concept test piece. I had clothespins to which I added auxiliary jaws that would close flat. So I drilled a hole to provide clearance for the screw head through these jaws and then drilled an axial hole to accept the screw.
Despite my sloppy woodworking (hey, it's a test piece, not a contest entry) and wood that chips too easily, the device works very nicely. Pinch it open, insert screw, unpinch, sand, pinch over cup to drop sanded screw. Rinse and repeat.
Once I get done with an ever lenghtening list of honey-dos, I'll make one with aluminum jaws and recycle this one into heat.