I look at Haralds web site for inspiration then go out and make shabby looking molds. Jetnoise I read somewhere that the mold should be at least 4 times as thick as the part you plan to make. So far I have had good results using West Systems epoxy, graphite powder and cabosil filler for a thicking agent. Those 3 parts make up my gell coat, they suggest letting the gel coat set up before applying any cloth I can see why that is a good idea since pushing cloth down against the plug would result in cloth pattern transfer. I always start with a light weight 1.5 oz follow it with 4 to 6 layers of 6 oz cloth in various directions keeping the overlaps under an inch and finish the top with a second light weight cloth for handling without gloves. after taking off the parting board you can make drill starts the width of the bit works fine on the flange for the second half to key into without worring to much about the depth or exact placement of each drill start (shown below). Bolt together is optional on larger molds it is prefered to clamps. Harald used threaded nut plates and bolts with a power drill turning them something his son apparently gets a kick out of doing himself.