GRP. A fabrication technique 1(for Bob)
When flat sheets of flat GRP or with right angled edges as seen below are not enough, several sheets can be joined together with resin and glass laid into the joins to 'weld' the assembly together.
The assembly needs to be held together firmly enough to maintain the right shape while the strips of glass are laid up, but in a way that will not intrude on the finished part.
A good way of doing this is to use lockwire 'sutures' as shown. I make small holes near the edges of the sheets to be joined with a sharpened bradawl (Basically a spike), using a piece of wood as the 'anvil'. I use annealed stainless lockwire. The sutures can twisted up to the point of pulling through the sheet and provide very firm location.
After the resin has cured the wire can be snipped through and is quite easy to pull out of the holes. The holes tend to get filled up during finishing.