You will need:
Candle wax (I buy cheap, broken candles at Salvation Army, garage sales, or other thrift stores)
Cardboard egg cartons (Styrofoam does NOT work)
Lint from your dryer (FREE:)
I use a size 10 can to put the wax in. When I was taught how to do this they suggested using a crock pot, but I didn't want to deal with the mess of cleaning it out or having an extra one just for this purpose as they suggested. I put the can directly on the stove to melt the wax.
Once the wax is completely melted, I spoon the wax into each individual well of the egg carton. The first few times I did this, I filled the carton with the lint first then poured the wax in (as I was taught). I found it sticks better when you put the wax in first then fill the carton with the lint. Below is a picture of both methods.
Below is a picture from the bottom on the difference between the two. Putting the wax in first definitely works better! The one on the right had the wax put in first.
The more lint you can cram in there the better. Cram, cram, cram it in there. This is the free part so don't be afraid to use it.The more you use the more affective the fire starter is and the longer it will burn. I often will pour more wax in over the top once the lint is in. There always seems to be a little more room for more lint. I even have other people collect lint for me. However, with a family of 8 we collect lint pretty fast ourselves. :)
Once the fire starters have cooled (putting them in the fridge or freezer is ok), you can leave them whole as they are and break them apart when you need one or you can break them apart and store them as individual starters. My kids enjoy breaking them apart so we do that before we store them.
One day when we made these, my son and I decided to turn it into a "science experiment" and time how long the a single starter would burn.
What it looks like when it is initially lit.
After 12 Minutes!!
After 18 Minutes!! It finally stopped burning at 21 minutes!