SpudFiles

Thanks guys! I eventually found them at an auto parts retailer. I found some solid core stuff too; though sadly the ID was a little larger than I hoped it would be (2.047"). Maybe someday I'll run my own tests on what foam core can handle before bursting. I kinda just want to blow up some pipe

you would be better off using 2" pressure rated pipe(which most small hardware stores carry) @ 100psi than 3" non-pressure rated pipe @ 30psi. performance and safety wise, plus it would be more compact and easier to carry