Cheng is the only person i know of that has detailed instructions on how to build your own concrete top.
i am the owner of Concrete Design Solutions in Columbus Ohio, we specialize in concrete counter tops. If you were at the home and garden show this year,2003, we were there with our tops in the national kitchen and bath association booth.
Making a good form is not to difficult a task. however, getting the right concrete mixture is! My advice is practice, practice, practice, once your cast in place top is poured it is hard to correct mistakes. feel free to call if you have specific questions, we would be more than happy to offer advice. 614.299.1900