I have discovered a way to make magnetic hatches that snap into place perfectly. Get the magnets from Three By Three Seattle (threebythree.com). The rare-earth (neodymium) magnets, called “tiny mighties,” are 1⁄8"-diameter. Find a position with enough clearance between the inside of the hatch and the model, snap two magnets together to locate their poles, and mark the front edge of the mating surfaces. (You’ll need to know how to orient them later.) Epoxy one magnet, mating surface out, to the inside of the hatch, and the other magnet, mating surface out, to a section of sprue. Snap the magnets together and prepare the model to receive the sprue end. You may drill a hole for the sprue end, but — and this is critical for a true fit — there must be enough “play” for proper clearance. You have to allow the magnets to determine the proper final position. You may paint exposed epoxy, but the magnets don’t take paint well. That shouldn’t matter if they are positioned well.
Tip submitted by:Greg HildebrandtWinamac, Indiana