Can anyone give me some insight as to the focusing mechanism and extension structure of the RB series of cameras. Does the base (wood?) moves on gear track? If so, is the track on the bottom or top of the base? I ask as I am buildiing a cigar box point and shoot camera and would like to incorporate an inch or two of extension. The RB mechanism seems the logical mechanic. Btw, is the front standard supported by a metal "L" bracket that attaches to the base. I can't tell much by the pictures I have seen. Thanks for any help you can provide.