Have you ever seen these? I came across my egg molds this morning. They are a little tricky. First you hard boil some eggs, peel them while they are still hot, shove the egg into the mold, and then drop the whole thing into some ice water. One of the tricky parts for me was having fresh eggs. The older an egg is, the easier it is to peel. The other tricky part is getting the right size egg. If the egg is too small, it doesn't fill up the whole mold. If the egg is too big, it is hard to close the mold and egg whites shoot out the sides.
All in all, the kids think they are fun and it only takes a few extra seconds to throw the egg into the mold since you are peeling it already anyway.