There are several things I've incorporated into my too bag of tricks over the years as a knifemaker..
1. Hockey pucks. I cut them in half and shape them to different surfaces, rounded, angled and leave some flat. I use them for doing the falt surfaces on knives, and when sanding stocks.
2. X-C Ski waxing corks. I use them for sanding stocks also.
3. 5/16" auto glass. I cut a piece large enough to hold a full sheet of sand paper. Then I glue the glass to a wood board. I then glue a piece of 150 grit paper, rough side up, on it and attach the assembled glass, board and sand papaer to at work bench so it's solid. I then place different grits of sand paper on the 150 grit glued to the board, with the 150 paper holding the working paper by friction. This provides a very falt surface to do any work requiring that the end product is flat, like the flat surfaces of knives. I also use it for gun parts that need to be perfectly flat. I have sand paper of all available grits from 80 down to 2000 that I use for parts finishing.
4' Plastic silverwear. I use spoons and knives, with the edges ground and finished to different shapes and sharpenesses to fit into places needed for stock work. I use a knife sharpened real well for glass bedding stocks to cut through the bedding before it's hardened so as not to harm a blued barrel, at the top of the stock parting line.
5. Leather. I have 8-10 oz leather glued to the jaws of my vise to protect parts when working on them. I also have different thicknesses of leather I use to hold work pieces so as not to harm blued finishes. I use thin leather pieces wrapped around wood dowells to serve as a backing for sand paper while sanding parts that have rounded surfaces. I also have different sizes and shapes of heavy leather, 10 oz stuff, that I use for sand paper backing for sanding parts when the situation dictates.
6. Cans of compressed air. I use them for cleaning out triggers, etc. After spraying gun scrubber in the trigger, I use the compressed air to finish the cleaning job. The cans of compressed air are sold at photo shops for lens cleaning.
7. Wood dowells of every diameter I can find up to 1" and in different lengths to use when need as a sand paper backing, with or without a piece of leather as the situation dictates.
8. Sissors. I keep several pairs for cutting jobs, including an old pair for cutting pieces of sand paper to sizes needed, from 80 grit up.
Plus the things mentiomed above; soda straws, tooth picks on different sizes, paper clips-all kinds, dental picks, old measuring spoons from the kitchen for measuring anything and everthing from powder to epoxy, old popsicle sticks for lots of things. You can use epoxy to serve as a bond for powdered abrasive on the popsicle stick to serve as sanding sticks when the epoxy hardens. Soap to use as a lube for stock screws. Old coffee cups to hold anything from pencils to trigger parts. Old marginine tubs for parts keeping....
Don