I used to make my own throwing knifes from diamond shape hand file by using a hand grander. To make the blade is easy. The hard part is to make the handle. I collected some plastic bags, melt it into black glue, wrap it around the end of the blade, wait it to cool off, and use knife to make it into handle shape. This kind of handle will not break when drop on the ground.What did your throwing knives look like.
My throwing knife look like this: