I read about doing this a few times last year and it appealed to me, it wasn't until the packing and sorting was well under way that I realised the extent of unused crayons we had. I went ahead and gathered up all the broken bits and also broke the complete crayons in half, the most time consuming part was removing the paper.
So on New years eve Each child made a rainbow crayon and I grouped the rest in like colour families.
The paper still allowed some of the wax through into the base of the muffin pan. I put them in the oven at 150 and checked them at about 3 to 5 min intervals. I think it took about 15 mins roughly.
I didn't take pics of the in between stages sorry.
You want the crayons to completely melt to a liquid and doing it at that temp really minimised the melting crayon stink to barely noticeable. Once the pan had cooled to a stage where I could handle it without oven gloves I popped them in the coldest part of the fridge for 1/2 an hour to an hour I suppose. The papers provided easy removal and peeled away from the crayon without incident.
Little Mr stunned me with an 'out of the blue' detailed crayon and pencil face, I did not know he could draw like this!
( I fear I label my Daughter as artistic perhaps at my sons expense )
Some of the crayons were glittery and it seemed to float to the surface giving an interesting sheen.
They are a great size for little hands and perfect for doing rubbing's.
A fun creative morning ensued.