If you need a uniquely sized shim, or spacer, that is rather thin, you should consider some items that you might have laying around and will give you the uniform thickness that you need.
Consider the following to use as a uniform thickness shim. They are inexpensvie items and things that you might have around your garage, workshop, basement or attic.
- Laminate Flooring
- Pegboard or Hardboard
- Vinyl Tile
One of my favorites is Linoleum or vinyl tile (the 12″ x 12″ stick on variety). If you have a couple of peel and sticks around, you can cut them to size and layer as needed. The best part here is that you can use the peel and stick backing to hold it in place.