I posted this elsewhere but I thought it would be interesting to see what folks here had to say about it...
I could not function without them. I have used a piece of hard maple with numerous holes drilled in it for hammering pins and such for a long time. It always sits on my bench to my left and gets used constantly.
Over at the drill press I have a chunk of heavy aluminum channel stock also drilled with tons of holes. I can always find some combination of them to ensure that my knife is sitting flat despite pivot pins and other protruberances. It comes in very handy for clamping since the work piece is up off the drill press table.
I just picked up a thick round Delrin bench block from Brownells. It has a groove on one side to hold gun barrels. I can't wait to start drilling and customizing it although I suspect I will use the non grooved side more. Wish it was a little bigger in diameter but I think it will do nicely anyway.
Wouldn't mind having a thick square or rectangular chunk of tool steel as well. Something really flat with a high grade finish would come in handy at times when a little adjusting is called for.
Just curious what others have used. Any special materials or shapes?