The wax from your old candles can be used to make new candles.
If you're a candle-lover, I have a reason for you to never throw out your 'burned down' candles again (or the wax that dripped off of the bookshelf where you had them sitting and onto the floor). Using your old candles and their wax to make new candles is a fun project and the only thing you really need to buy for this project is a package of candle wicks (around $3-$5 at your local craft store). During my recent bedroom renovations, I added three awesome candles to my decor without buying any new candles via this project. Of course you can use the candles anywhere in your house (but they're sexier in the bedroom!).
How to make new candles from old candles and their wax:
1. Locate your old candles. If they're dirty or dusty, be sure to wipe them off.
2. Heat up water in a double boiler. If you don't have one, you can easily rig one like I did just by placing a pot with water over the flame and a smaller pot inside of that pot.
3. Use a hammer and nail, or anything sharp and powerful, to break the candles into chunks of wax. (I used a screwdriver).
4. Once your candles are all in chunks, start placing the chunks into the top of the double boiler (the top pot) so that the wax can melt.
5. Washing out the mold you'll be pouring your wax into. Glass and metal work well if you plan on keeping your candle inside the mold. If you just want use the mold to shape the wax, make sure you coat the interior of the mold with cooking spray or some kind of oil so that the wax will easily pop out once it's hardened. Once the mold is cleaned, place the wick inside of it in the center. When your wax is melted, pour it into the mold.
6. Wait for the wax to dry (this was an overnight process for me) and then trim your candle wick once it is dried. Enjoy! You'll never have to throw out an old candle again by employing this D.I.Y. trick at home. It's a great way to reuse candles, wax, and even soup cans from your recycling in my case. Beeswax and Soy wax candles are green candle options, so try to work exclusively with these types of waxes if you can.