Door Hook
The Story:
My wife was about to buy an "over the door hook" to hang my kids' knapsacks when I realized that I could probably print one. I found a great model of a hook on Thingiverse that has an extra curve in the hook that makes it stronger. Before I printed it I engraved it with my kids' names and a picture of a knapsack, just for the fun of it.
The hook with knapsacks
The hook with knapsacks
Close up of the hook and engraving
Close up of the hook and engraving