Make easy DIY scented candles with the Glade wax melter.

This works so well. And you can just recycle the candle wax from random sources again and again.
The wicks are from common tealight candles often sold in bulk packs.

If you want to remove a candle from the dish then you can put it in the fridge for a while, and the wax often shrinks enough to free itself completely.

Once again I'll mention that you shouldn't have the wicks lit while the wax is also being heated on the unit. If it gets too hot the wax could burn with excessive smoke.