I for one do not have a candle warmer a) because I'm
Take your worn out candle and place it on a baking sheet or pan of some sort (really anything that can go in the oven will do. I use a 9" round pan because its easiest for me.
Put the pan on an eye of your stove and turn the oven on to a little bit higher than LOW.
(Please excuse the dirty stove knob...but after all we do live in this house!)
Place the candle in the center of the pan...
And wait for the aroma of that favorite once useless candle fill your home.
I know it's not the prettiest way to heat those old candles BUT it does work and it is done with things you already have at home.
(Also this can be a good way to get those plastic labels off of the glass candle containers that can be repurposed!)