Ok, so mine wasn't really literally free, but that's coz I didn't wanna sacrifice any of my belts.
So I made mine from a discarded belt bought from a roadside stall at a Thieves' Market for $1. I was looking for a nice colorful one. =) Got the other materials already at home, or someplace cheap too.
This strap I made is not really adjustable, so measure properly. Or you could improvise and make it very adjustable too! I didn't think about making it adjustable before I started cutting... =P
Anyways, read on!
Step 1: Materials
As listed in the photo:
1. PVC sheet from a previous project (which didn't come to fruition coz of my laziness)
2. A pair of scissors
3. An old belt that is nice!
4. Buckles (you'll need 2 pairs)
5. Nylon strap that fits through your camera's lugs
7. Needle(s) (I only used one)