Raising three children by myself made money very tight, especially at Christmas, so I was always trying to come up with new ideas which would stretch a dollar. One year, while cracking walnuts, I came up with the idea of using the walnut shells for tree ornaments. I carefully separated the halves, put money in them, a dollar down to a nickle, then glued them back together using a paper clip for a hanger. Imagine the surprised faces when the kids "cracked" the walnuts.
I used to do this - but put fortunes inside instead of money - I called them "fortunuts". If you use a thin wedge in the "hole" end of the nut, slip it in and turn it like a key - you are more likely to get a consistent split down the seam with less cracking. In fact, Japanese walnut crackers are small aluminum pieces shaped like hearts that you slip in and twist.