I made a few corner angles to experiment with the idea. I made a mold using that new recycled plastic material. I bought a board, cut it in half lengthwise and screwed the 2 pieces back together at 90 deg. Simple and it works, no mold release required. My conclusion is that it is probably faster to make the joints directly on the boat. The angles also have to be quite thick otherwise they are too flimsy and will be impossible to bond to the boat, unless complicated clamping is possible. More info later when I actually assemble the boat.
With the help of my 2.5 year old son I completed my laminating table. It measures 5' x 25' and is sealed with some latex varnish. I am ready to start laminating as soon as I get my vacuum pump, peel ply, breather etc... It takes forever to gather all the required stuff!!