This design is modified from a wing-nut tool that I've seen. (Origin unknown) It's made from 1/2" nylon plate (with some optional aluminum retainers). I've made it pretty universal, so that you can bolt a big bar to it or have a central nut for use with an impact wrench.
I priced it (nylon plate only) out at emachineshop: $70@5 pieces, $45@20 pieces. If someone wants to take on the project (maybe with their own laser/waterjet), I will supply the file for free. If I have to get involved, the price will get a lot higher.
