sfstu:

You'll probably want to make sure you have a fast-blow fuse in there too, otherwise it'll transmit enough before it goes to blow the delicate parts on the board before it goes up. And make sure if its close to the styrene that you insulate the area... something that won't transmit the heat... think someone makes a thin insulating tape, but some metal-foil duct tape should do. It'll reflect the heat away for enough time to avoid damage to the styrene. Even better would be put the foil onto some of the craft stick-foam I mentioned elsewhere, then stick the foam to the styrene. Extra insulating layer, and expendable if worst happens.