Now in this case with these Dianauts, where I am using magnets...there will be a little divot in the mold to actually hold the pin. But being a smush mold it will be subject to movement before I close it, so every little bit helps.
More importantly, the magnet was used to stimulate your thinking beyond the box into how you can use silicone molds to your advantage. How you can use magnets or anything else to help you create the mold.
There are no set rules to making silicone molds. You are only limited by your imagination. For another example check out the 4 piece mold I made years back so I could double pour.
EDITORS NOTE: I just noticed my post on the 4 pc mold focuses on the result not the mold. I'll be expanding on it with mold pics. Im sorry.