I used to go to Lowes or Home Depot and buy an individual ceiling tile to put on top of my building table. I could shim it to make it nice and flat and it was easy to stick pins into. I stopped the other day and the store I was in did not have individual tiles for sale, you had to buy the entire box. Couldn't find anyone to ask, maybe you can open one of the boxes for an individual tile, not sure.
Just wondered what everyone was using as a top for their building boards these days. I looked at the pink insulation foam, but you had to buy a huge sheet of the stuff and cut it down to size.
Thanks
Vince