Making molds and casting is usually an involved and time-consuming process, but if you’re making something on the smaller side, Instructables user LoSkana suggests using hot glue. He says:

The advantages is that the casting process is very quick, as you don’t have to wait hours for the resin to harden, and the resulting replica is flexible, and can be safely used even with sword going around it without risking of breaking it.

His method involves hot glue sticks, a small electric oven, silicone, and a few other odds and ends. He started with a master and prepared the mold material from silicone, flour, and mineral spirit. He melted the hot glue in the electronic oven — which is not something you should do in your home, only in a ventilated workshop or garage. Once the colored hot glue is prepared, he says:

Put some bits of coloured hot glue on the mould, approximately the mass of the master plus a little more. Turn on the electric oven, and the glue on the top will melt, slowly falling down and filling each detail!

The time needed depends on the oven and the mould, for these little pieces 10 minutes were enough. I left the door of the oven open, since I wanted a slow heating (too fast and the hot glue will start to “boil” and form bubbles).

See more at Instructables.