Unless you could get an acrylic plate wth a seal around the edge to go over the bath, got the bike pump working in reverse and reinforced the bath, you might stuggle even with some proper elbow grease
So you get in the bathtub with the bike pump and have the hose connected to a nozzle going out. You might need something stronger that shrinkwrap depending on what you get, but your bathtub is invariably able to handle 1 atmosphere of pressure.
Or, hear me out: a bathtub, some shrinkwrap, a bicycle pump and so e good old fashioned grit and determination.
Unless you could get an acrylic plate wth a seal around the edge to go over the bath, got the bike pump working in reverse and reinforced the bath, you might stuggle even with some proper elbow grease
So you get in the bathtub with the bike pump and have the hose connected to a nozzle going out. You might need something stronger that shrinkwrap depending on what you get, but your bathtub is invariably able to handle 1 atmosphere of pressure.
That’s the hard part: if it’s fibreglass then it’ll crack, and you’ve gotta stop the plug from unplugging itself and letting all the air in