I tried to make some with the blue can and I was able to get them out by pushing a marker through the bottom of the pvc. The only proplem is that there are air bubbles in the middle of the dart... great great texture other than that, though!
I think I've said this before, but I work at ACE Hardware and we sell this stuff. It comes in three sizes, blue-small holes(for around windows and doors), red-medium, black-large gaps and big holes. Holla!