RE: Mold questions
What I used were the self adhesive rubber/plastic door bumpers like the ones on the inside of your kitchen cabinet doors so they so not bang when closed. The come in all sizes and shapes, hemi-sperical, round-flat, square, etc.
Place them onto the parting board and remove them after you mold the first half. Wax and PVA the hole and lay the other half of the mold. The alignment is tight. In fact the 2 halves snap together.
Al