As for router bit bumpers, I use Rockler’s “spaceballs.” I put a small dab of adheasive contact glue on the end of a Q-tip and apply it to the end of the router shaft. Drop in a “spaceball” and you’re good to go. One “spaceball” fits all – 1/2″ or 1/4″. It lasts forever, it seems. Only had to replace one, once.
– Gary Storme