Formulator ™ Simulator
The formulator™ has gotten excellent reviews as a wrist training device. Unfortunately, they sell for a hefty price, that is beyond my means. I designed the above one with the help of Gruntbrain's site and anson at the Gripboard I ended up using 2X4s as the top and bottom. 1X4s would be fine, but I had a bunch of scrap 2X4. For padding I used pieces of small puzzle mats. They were available very cheap at Wal-mart in the toys section. They work great as padding, as they are thin, but very firm. The pads were attached with staples and tape. A 1" drill bit was used to drill a hole in the center 2X4. I filed the hole a bit with a wood file. I then pounded the pipe in with a rubber malet. It is important to use a rubber mallet, a steel hammer will damage the threads. A hole was drilled threw all the boards and pipe. They were bolted together. A few nails on each side also help secure the unit. 3/4 inch pipe was used throughout. I used two hose clamps to hold the weight in place. I wouldn't recommend hose clamps for large or balistic movements, but they are fine when small movements and not a ton of weight is involved. I might cover the foam and give it a paint job at some point, but it's perfectly functional without either.
Your hand size will dictate how much padding you use and how much wood you put in the middle. On the photograph on the right the darker wood, with some black paint on it, is a spacer. It makes room for my hands. NOTE: If there is a little too much space you can wear a pair of gloves, thin leather to thicker winter to give a tight fit.
In addition to the one on Gruntbrains site, I saw an excellent one using just a straight pipe and a floor flange attached where my pipe goes threw the center portion. Unfortunately, it seems to have dissapeared from the Gripboard.
In the bottom picture you can also see my work bench. I attached a vice to a 2X12 that fits in my workout rack. It also functions as a bench and my kitchen table when flipped over!