First: Thanks lugh for this marvelous piece of information!
I want to allow myself to add some tidbits - tried and true:
- pieces of the same diameter can be connectec by simply wrapping thick PE-foil around the two pieces to fix the foil with some wire wrapping alufoil around and to put it into the oven at about 130°C for 10 minutes. The prestretched PE will shrink in the heat and fix and seal the pieces gas and liquidproof. If not needed anymore, just cut open with a knife. A hot-air gun can be used instead of the oven cure in special if bigger parts are to be connected.
- often no machined aluminium mold is necessary, a simple gypsum mold will do it. Alufoil prevents sticking but oiling the gypsum with saladoil will do it also and better in most cases. (oiling the alufoil slightly is a good idea anyways)
- last not least:
PE is a good reducing agent for metaloxides for example. Dont waste your waste - use it!
oRg