I decided to try replacing an aluminum spacer & multiple shims on the idler pulley assembly I was using on a Delta printer with a printed spacer. Giving it a wider Diameter where it connects to the endplate seems to give it more support for a longer bolt than a smaller diameter aluminum spacer. I was originally calling this a shim, but spacer seems to be the correct name.
The main picture shows how I used it with the idler pulley at the top of a Delta printer.
If you are using this with wheels with bearings in them, make sure you use a diameter that will not interfere with the wheel rolling. I initially put the larger diameter against the wheels & they did not roll at all. The 2nd & 3rd photo should show what I mean by this.