I just bought a co2 canister and what I thought was an adapter valve that would allow me to put 5/16 tubing to the canister. I saw a few DIY chambers and most people weren't using regulators but $2-$3 adapters. What is this actually called and does anyone know where I can buy one? I dont want to go and buy a $60 regulator if I can use a $2 dollar piece.

I was going to use dry ice but the rat production is too sporadic for that to be feasible.