I made this thing to avoid egg shells in my soft-boiled morning egg.
You put the 3d printed part on top of your soft-boiled egg, lift the weight and let it go. Then the Egg Cracker cracks a nice line around the top of your egg, ready to cut off with a knife.
https://youtu.be/KymLRvwMLoo

To make this thing you need:
5mm stainless steel rod (I used a tent peg)
1 metal ball or other metal object that can be drilled through with a 5mm drill. (I used an old tire nut)
Some super glue

When the part is printed you slide the metal ball over the tent peg and glue the tent peg to the top of the printed part. There is a hole that should fitt on the top of it.

Happy Egg cracking (Topping)