I guess some of you think you are entitled to the specs. I like the one answer here, just buy one and copy it. Must be the "in" thing to do, the Chinese do it.
Why not buy one and try it and if you think you can do better start having a grinder grind you some up to test an see if you can come up with a better mouse trap. Of coarse this will have to be done within certain design perimeters. If you do after years of trying please have it mapped and share it with everyone.
Don't worry about the costs involved or time you had put into it as all the grateful enthusiasts will send you more than enough money to make it worth it.