Horrible Fright lol! That is funny that you mention those clamps because I was going to buy them. The first clamps I bought where from Harbor Freight.
http://www.harborfreight.com/4-in-ratchet-bar-clampspreader-62242.html
They sucked because I couldn't squeeze them down hard enough so when I injected my mold plastic oozed out the sides. The cool thing was I took them back the next day and they gave me my money back and I saw the clamps you use Bob. I was going to get them but then I thought they might suck too because they are from Harbor freight. So instead I bought these clamps from Home Depot.
http://www.homedepot.com/p/Husky-3-in-Drop-Forged-C-Clamp-97891/205132116
I think I might just buy the Harbor Freight clamps anyway because they are cheap and I see that they will let me clamp more molds together.