Make sure that they aren't drippy and that they won't get soggy.
2
Softer crayons will result in soft, drippy candles that won't last long.
3
The kit has got everything you need to make gorgeously gooey drippy bouncing slimes and at the same time gives a valuable science lesson.
4
They don't sport a large collection as some of the other sites listed above, but you will find some different ones like Asian fonts, Drippy fonts and Retro fonts.