I had a freak accident once, which I doubted was very serious, but due to not knowing the mechanics of the injury, I wanted to keep weight off of my foot to keep from hurting it more.
The solution was close at hand -- my broom.
All you need to make an emergency crutch is a broom and some tape. As it turned out, the length of the broom handle was about right for me. If you are shorter than I am, you might want to cut some off the end of the handle.
Step 1: Tape It Up
After you get the basic form made, wrap it all with duct tape and off you go! It could be a little cushier, but it's not bad, and it does the job.
I could have parted the bristles in the middle and bent them forward and backward, but that would have eliminated some of the bristle cushioning under my arm.
The broom handle was about the right height for me. If you are shorter, you might want to cut some off the end of the broom stick.
A store bought crutch has a rubber tip on the end to help prevent slipping. The broom does not have a rubber tip, so be careful with each step you take. Better yet, be careful with each step you take before the accident and then you might not need to make the crutch at all!