Simply peel your old crayons and sort them into colors:
Place them in your molds* (Do Not Forget To Spray The Molds First!!....I did the first time- talk about hard to get out!). Heat the oven to 225 and bake just until melted (about 8 minutes)- place the molds on a cookie sheet for stability:
TIP: This part is a little tricky, because if you melt them too long the wax and color separate (it is better to have some chunks still in there). Also, it helps to use only one brand of crayon as they all have different levels of waxiness.
Let the crayons cool completely before removing them. Then you can line 4 in a snack size ziplock bag and staple a tag* to the top (I made one for my kids and you are welcome to use it or copy something like it for yourself).
*I bought some cheap silicone molds in the $1 section of Target.
*Here's the tag I am using- click on it for a full size printable image: