I had a similar project going, which resulted in a pretty extensive discussion thread:
Ultimately, I went with a simpler design, although I may come back to this.
The importance of a mock-up, in my opinion, can't be overstated. It doesn't take too many screw-ups before you've spent about the same in materials as what a commercial version would cost (not to mention your time).
Like Jerry, I look forward to seeing the results. Please post (progress reports are good, too).