RE: making a mold
That's what I do too Steve. That way if I have to stop for the day I can just finish the half I'm working on and throw it in the vacuum back with some peelply, release film, and bleeder cloth, then set the vacuum to the amount I want and walk away.
I made templates to cut out the cloth and it gets pushed up to the edge. I use a marker when I draw around the template on the glass. This way I have a colored line that helps me see when it's pushed to the edge.
Seaming the molds (install seam tape before joining halves and add epoxy/silica mix with a syringe): I finish the two halves by wetting out seam tape with epoxy on some mylar or Monokote or whatever and then crease it and add it to one half of the mold. Next I mix up epoxy with a silica thickening agent and it gets applied with a syringe along the whole edge, even where the tape is to help fill in the seam. Then the areas I can't get to with seam tape when the halves are joined also gets a bead of silica epoxy so they will bond without tape (usually the tail and vertical stab). Now that the first side has tape that is folded over I apply the other half of the mold and all I have to do is press down the tape with my hand as far as I can reach and then I use whatever I can to press the rest down. Sometimes I will put a very thin layer of epoxy to the 2nd mold half to help the tape bond.
Tim