This is a cute waste-not idea from Martha Stewart, but it’s been done by many others as well. Teacups are ideal for this particular trick as they are already designed to withstand high temperatures, but you can use canning jars and other heat-safe containers as well.
For my DIY Christmas I spent a lot of time scrounging second-hand stores for things I could use, and one day my mother happened upon a large quantity of beeswax sheets just there for the picking.
And yes, I picked. I also picked up some old teacups and had some that were missing their saucers donated by my parents.
I had to buy some wicking from Michaels, and I found these handy wicks that were pre-waxed and already had the sustainer attached to the bottom.
All I had to do was stand them upright in the cup and I was set. Easy-peasy.
So you take your old candles, or your beeswax, or whatever, and you chuck it in a double boiler. I used the equivalent of two sheets of beeswax for each cup. Just tear ’em up and let them melt!
Be patient. It takes a little while.
Make sure it’s completely melted before removing from heat.
Now, very carefully, pour the hot wax into the cup. 
Leave that to sit a while. See that little blip of wax on the side of the cup? Fuhgeddabowdit. You can just chip it off once it’s set.
If you return your waxy bowl to the still-hot pot you can wipe out the excess wax with a paper towel.
This will mean you can experiment with other colours of wax as well.
Once your candles are set and cooled you can trim the wicks to an appropriate length and give ’em all away!
Ali Does It Herself 