by mattb » Tue Jul 07, 2015 6:28 am
Glue gun and cardboard can make a custom size mold box, legos work fine, or masking tape and cardboard. It doesn't take much. I keep thin cardboard on hand. I like the smooth finish cardboard that some has with shiny, colored artwork. Mostly I use cardboard and tape. I have a small number of plastic boxes I use for stuff like wheel inserts and little pieces. I have been known to use modeling clay shaped around a small part and then used for a one time mold. You just have to remove the master part easy so you don't distort the clay mold.
It is amazing what you can do and it becomes a challenge to make it yourself!