Outer Limits 4x4 Board

Thought I would let you know how I made a cheap roof bag.
I recently bought a double sized foam bed for camping which folds into 3 pieces, since I am fed up with blow up mattresses.
I need a waterproof bag for it and after getting quoted $150 to get one made up from vinyl I decided to make one on the cheap.
I bought a 3x3m plastic tarp from Big-W for $5 and cut it up to make the bag. The shape is very easy, just a rectangular box. I needed a way to glue it all together and after trying several types of glue, nothing would work.
After I spoke to a canvas maker he said they weld them with a radio-frequency air welder, which I dont have.

So I welded it up with an ordinary iron.

This took quite a bit of experimentation but after trying on lots of bits of tarp I got it to weld strong, waterproof joins.

Ingredients:
plastic tarp
plank of wood
aluminium foil
iron

The plank was covered in the foil, the tarp on top, then more foil. I found the right temp of the iron to be about 3/4 on the speed about ants pace.

Here's the pics:

Nice work

excelent work, good idea with the Tarp and iron, congreats on the neat completion

interesting... maybe i can make a buggy cover