Hey ya know... actually thought of doing that, making wooden washers to go with it. From a woodworking perspective though, would be harder than you think. Inside hole of washer piece of cake, but don't have a hole saw large enough for outside dia, thus would have to do it freehand on bandsaw (or make circle jig) and try and finish sand perfect circle. That's easy when it doesn't have to be dead on circle, but with the nut/bolt your eye would perceive a non-perfect circle first glance, and I unfortunately am a perfectionist and that would bother the #$&# out of me. Could do them on lathe, one long cylinder and then slice them like carrot or celery stick... but then grain would be oriented wrong, would break easily for something that thin. Have to think about it some more.
Glad it made it down there MB