Building a hovercraft.

[Orpackrat]

Not the foam that you sleep on or use for cushions but the insulation foam sheets. You would need a few sheets and stack them for enough support (1"-1.5" should be plenty).

[gotbass7]

that probably would work as long as you arent gonna ride on it.

[Flying_Salt]

This might help

My friends and I have found that a tarp-like thing, such as the ground cloth from a tent, hold air better than something like trash bags.

[gotbass7]

yes i used the tarp too. its easy to cut to and if you make mistakes its easy to cover up with ducktape and its much more durable