This is the quickest project ever. It took me a lot longer to write it up than to do it.
Approximately 80 inches webbing, 1" wide, any non-stretch material is fine
The same length satin ribbon (optional), 5/8" wide
2 D-rings to fit 1" webbing
Note: I bought all this for about $6 at my local Ben Franklin. You can probably get it for less if you don't live on an island in Alaska. Webbing and D rings are also pretty easy to scavenge or thrift, if you just keep your eyes out. Straps on cheap or old bags, old backpacks, etc. I didn't feel like digging through my camping gear in the basement to find the random lengths I know I have down there. You can also get all sorts of cool webbing, if you live places other than an island in Alaska.
Sewing machine (here's a tutorial that uses no D-rings and hand sews)
Ruler or measuring tape
1. (Optional) Attach ribbon to webbing down the middle lengthwise by sewing a straight stitch close to the edge of the ribbon. I did this by setting my needle slightly off center and then lining up the edge of the ribbon with the middle of the presser foot.
2. Cut a 37"-ish length of webbing and attach each end to the flat part of a D-ring by poking it thorough the D-ring, folding over about 1/2" and sewing it down. I used a wide zig-zag and went back and forth about 5 times to make it really secure and ensure I caught the loose ends of the webbing and the ribbon. You could melt those prior to sewing if you have a flame handy and felt like spending another 5 minutes on this project.
3. Now cut two 21"-ish lengths of webbing. Form a loop by folding a piece in half, and then attach both ends of this piece to the curved side of one D-ring, the same way you did in 2. Repeat with other 20" piece and other D-ring. That's it! You're done!