Coehorn mortar
http://youtu.be/E2l9NU2a-XY
Type: Posts; User: nevada
Coehorn mortar
http://youtu.be/E2l9NU2a-XY
Most of these are made using old oxygen bottles.I'd still be worried they would burst.Its probably only 1/4 inch thick.
"punkin chunkin" has a better following.You can grow the pumkins in a mold....
http://youtu.be/v2DlLHFU3dA
http://youtu.be/XQdf_J9MgxI