i have made them from not bondo but alum epoxy filler dont remember the name of it but worked ok trick was not to over heat the lead .they lasted o few pours .i drilled sprues to pour the lead in .had to re drill them a few times till they worked at first they were too small and the lead set up and plugged the mold .after a few casts were made the mold warped and got soft time to throw out. do it makes dimond jig molds and ya can fimd them on e bay too but for the most part jigs are cheep enough i buy them now .