Here is an example of how a mistake can turn into something useful. This knife was originally supposed to have a full tang handle and cow bone handle scales. I forged the entire knife to the shape I wanted only to find that I forged the handle too short. After a bit of thinking, I reforged the handle a bit. I then cut a slot to match in a piece of deer antler. A few pins and some turk knots later and here we are, a fine patch knife with a tribal feel to it.
I only wish all my mistakes were this easy to fix!