For wood ones, I just spin my own. I have also cast my own. I just take a 3/4 dowel, drill a 1/2" hole in the center and place the desired object in the center, then cast resin, but you could do the same sort of thing as a "doohicky" with just using clear inlace, because the amount of casting resin needed is so miniscule. A doohickey compliments certain pens. A great addition to a pink pen, or you can cast a flower pedal pen. Then...you can also go to the auto parts store and look for valve covers and lock covers. They have skulls, dice and other cool looking things. Unfortunately the LED covers are too bulky for a pen..at least the ones I've been able to find. Lots of options all around you, just use your imagination.