I actually saw this on youtube today & thought about you guys!!! She did this in her car. She didn't say how hot it got but it took about an hour from her comments.
Wow how awesome! I was looking at it and wondering if I could do it just by leaving it outside.
I live in Texas and we've been have 100+ temperatures for the past 2 months almost.
Well.. crayons can and do melt in cars.. maybe you could.