All you need is a few basic items and that leftover wax won’t go to waste.
They become hard to light and won’t burn very long anymore.
Place your spent candles on a cookie sheet to bake at your oven’s lowest temperature.
While their wax is melting, hot glue a new wick to the bottom of a mason jar.
Check out the complete guide at the link below.
How to: Make a New Candle from All Your Spent Ones| ManMade