Whether you're making a stunt dummy for a school project film or to test out your latest stunts, you can make a stunt dummy with an easy trip to the craft store. Depending on how much you're willing to spend to get a stunt dummy, you'll have gone either way that should be able to withstand some testing.
If you want a really fancy stunt dummy visit local thrift stores or the internet and purchase a mannequin. Dress up the mannequin and use it as a stunt dummy.
If you want a stunt dummy that is made up only of soft things, you can make one out of old clothes and craft store stuffing. Sew a pair of socks to the bottom of old pants, then sew the top of the pants to the bottom of a shirt, for the head, cut the end off of an old pillowcase and sew it to the top of the shirt and then to a hat. Sew one shirt sleeve shut, but leave the other shirt sleeve intact so you can stuff the dummy. After you stuff the dummy, sew up the last shirt sleeve. Now you have a stuffed stunt dummy.
If you want a dummy that is still inexpensive, but has a bit more substance, buy a few large sheets of cardboard from your local craft store. Look online for dummy patterns and then create your own dummy pattern. Trace all of the pieces of the pattern onto the cardboard and then cut them out. Connect all of the pieces of the dummy front and back with duct tape. Then take layers of newspaper or tissue paper and attach them to the dummy's body parts. After you have your dummy at the desired thickness, add some clothes. Your dummy is now ready for testing. The more separate parts you have for your dummy, the more agile it will be.
A little bit fancier of a stunt dummy can still be inexpensive, but may require more creative work. Go to a local wig shop and ask them if they have any Styrofoam heads for sale. If you can't find a head, you'll have to purchase a Styrofoam ball from the craft store. Purchase other types of Styrofoam parts, long skinny parts for bones, medium sized blocks for feet, and small balls for joints. Use an old wire hanger to poke holes through each Styrofoam part and then string them together where you want them to move. Once all of your pieces are tied together, you just need some clothes. This type of dummy is extremely agile, but it is also very durable, especially if you use good string to tie the body parts together.