"It's actually like the batik process where
colors are protected with wax and the wax later removed with heat. ( usually
held near a candle flame. This is why it's not possible with the little ones.
Actually, even with lots of the big ones that I have.) "
You can use a toaster oven to remove the wax too. Make a rack of 3 nails to elevate the egg, put the rack on a cookie sheet to catch the wax, balance the egg on the nails, put the whole contraption in the toaster oven at a low heat until the wax melts off the egg and collects on the cookie sheet. Safer than using an open flame, and you can do a whole batch at once.