They are really pretty easy to make and can be a great product to have. Good luck with yours and keep us posted on how it turns out.
I took the easy way out on one 'hot box'-type extention I made. I bought the four outlet box that Hubbell makes. It really isn't much harder to wire two outlets in an electrical box though. There is also some info floating around on how to star ground the two outlets instead of wiring them in parrallel.
