Figured I would post how I make molds since it comes up often.
This is how I make crankbaits out of Aluminite resin.
Things I use: silicone, legos, mold release spray, modeling clay, sharpie, wax board, wax tack (I forget the actual name)
Step 1 is to make a box out of legos big enough for whatever you are trying to copy. Next tack the wax board to the bottom of the box and fill it half way with the clay. Now press whatever you are trying to copy into the clay until you reach the parting line. Smooth out the clay and press the butt end of the sharpie into the four corners to make keyways. Mix and pour the silicone in but spray the inside with mold release right before pouring. Wait the required time (like 12hours) and remove everything from indide the box. Clean off any clay from the master and the silicone half. Now place the silicone half on the bottom of the box, spray it again with mold release and pour the other side.
Some things to be careful about; make sure to spray with mold release as the silicone will not come apart and mix the silicone correctly as it may not harden.
I cut the pour sprues after I am done personally but they can be molded in.
When pouring the baits use two blocks of wood on each side to clamp the mold together. The wood keeps the mold from deforming while clamped and the clamps keep the mold from flashing. do not overtighten the clamps or the bait will be deformed. If you are getting incomplete pours you may have to cut a small air vent (look at some of the aluminum injection molds for examples).
I think this covers it but if there are any other questions just ask.
Allen
