It's an interesting idea, polyglot, but probably a bit beyond my capabilities at the moment. These holders are not particularly simple, having a toothed track down one side which the scanner uses to draw it in, and various registration features; not to mention all the lips and steps and edges on the piece which may or may not be important - some investigation would be required first to understand the scanner's loading and stepping mechanisms to see what features are really important. In addition to making accurate measurements of all the critical dimensions, one would need to have reasonable proficiency with a drawing program, and of course access to a 3D printing machine. Not to say that any of this can't all be done. But I'm just not there yet.
I'll keep it in mind as a long term project though, if I can't find a used one.