In the meantime, I've added something to the gym that will hopefully help me in my rehab and then eventually get back to where I used to be (well, I'd take close). Here is my DIY reverse hyper:
DIY Reverse Hyper in action! Rock solid!
I was inspired by this site: http://www.home-gym-bodybuilding.com/homemade-reverse-hyperextension.html
Now, I don't have a cage, I have the fabulous Rogue Fitness S2 squat stand. So I had to tweak the design to make it work with the S2. I have the safety spotters which is what the contraption sits on. Also key to the design is the plate storage - load these bad boys up with a bunch of weight so the rack doesn't rock. I have 410# on mine. Note use this setup at your own risk. This hasn't been tested by Rogue. I don't plan on using massive weight for this, and I don't weigh that much so it should be fine. However if you're a big dude and want to put on a bunch of 45's, well, good luck and don't tell me I didn't warn you... :)
Here was my first design (with parts list):
So I bought all the supplies, and then it sat for several months until I finally got working on it. As I was putting things together, I realized the 2x10 material was going to make this thing heavier and look pretty rough (note: I had some 2x10 left over from my jerk boxes). So after thinking about it, I checked out my wood pile and saw that I still had some 3/4" plywood leftover from my jerk box project. So I modified it and used that instead. Much better choice. It is definitely lighter and I think looks nicer.
Rogue Fitness dip belt that does double duty as the strap for my feet. The 1.5" pipe nipples are about 1.875" in diameter, so just a tad short of the 2". My lock jaw clamps don't clamp tightly, but they don't slip off. If you want, you can put several layers of tape on the pipe nipples to build up the diameter so your clamps will stay in place.
So for the top I went down to Joanne's Fabrics and picked up some vinyl material off the sale bin for $8. Pretty thick with a slight texture. Use whatever you want though. But try to get something fairly heavy duty.
Here is the foam I bought: http://www.onlinefabricstore.net/foam-and-pillows/foam/specialty-foam/rebond-foam/1-x-24-x-72-rebond-foam-.htm - I double stacked it so it is 2" thick. Used spray glue to hold the two pieces together and then used spray glue between the vinyl and the foam. Not sure how much that will help, but seemed like the right thing to do. There is a thin layer of wood (1/4") on the bottom of the foam - it is needed to staple the vinyl to. More spray glue there as well. Folding the edges takes some time and material cut away - take your time at this and you will get it to look pretty decent. Then I secured the pad down with a few 1.25" screws from underneath the plywood. Keep the screws to the outside to avoid getting poked by them (I don't even think it is possible with all that padding but might as well play it safe).
Anyhow, all in I'm probably about $130 give or take. Here is what you need to make one:
3/4" plywood - the top platform is 20"x32". Adjust to your desired size. Some might need it wider. The side walls are about 5"-6" tall. I have two braces of plywood - one at the front end and one in the middle. The last brace at the back end where much of the stress is is a 2x4 cut to size. I glued and nailed everything together.
The pipe is 1" galvanized for the supports. Those are approximately 54" long. Two are required. You'll need also the following pipe:
(2) 1.5" Tees
(2) 1.5" nipples, 3" long
(2) 1.5" nipples, 8" long
(1) 1.5" pipe, 24" long
(2) EMT couplings hacked in half (or you can just buy four)
(4) Conduit anchors to secure the 2x4's at the safety spotters to the main pipe (not sure on the size, just grab the package and test it on the pipe while you're in Home Depot)
Note that you can totally downsize the swing arm if you want. This might be important if you want to save money or use 1" standard plates for your weights. Just use a reducer at the top T-fitting and then get the appropriate sized pipe/nipples/T-fitting. Don't skimp however on the main cross bars.
Hope this helps. Leave comments if you have questions.