My main slingshot is shown in the first picture. It's made of red oak, using a scrollsaw and various rasps and files. It's finished with a beeswax and olive oil homemade finish (just like my bow, in my other instructable). The bands are simply chained rubber bands, which I switched to after trying tripled flatbands (which didn't work because they were thin and didn't last long individually) cut from a physical therapy latex exercise band and then trying latex surgical tubes (too powerful for what I usually do, which is shooting BBs and not larger steel shot). The bands are attached to a paracord loop on either end that are fastened securely into the top with screws and JB weld (known as "spanish style" on some slingshot forums)
To carry the slingshot around, I made a nice pouch out of woven paracord, inspired by the Leatherman Tool Pouch instructable posted some time ago. It works pretty well and hooks onto my belt with a carabiner. Really useful to carry on hikes or camping.
The other slingshots are also red oak, except for the funky shaped one, which is pine. All the others are not finished with anything -- only bare wood for now, which feels really nice to the touch. The funky shaped one's bands are an experiment of mine: chained rubber bands, a lot of them per segment, with all the bulk lessened by a rubber band that is tightly tied around the center of each segment's bulk. It shoots hard. Another slingshot is bare, with no bands, and the other one is with 3/8" surgical tubing (it can kill!).
If you like it, please vote for this in the I Made It Photo Contest! If I receive a leatherman multitool, my DIY isn't only limited to my home -- I can't name the multitude of times I've been stuck during camping, hiking, or just somewhere in the city where I need a pair of pliers or a screwdriver to fix things... Or make something, for that matter. Thanks!