need some lens mount help!

Hi,

I have another take on IHKim's macro tubes, I was hoping I could pick up some really cheap tubes from ebay and just make a cable connection at each end which could be adjusted depending on which tube is in use and yes! a reverse ring takes care of one end of the mount so that is on the list. but I wanted to start with tubes which were at least close to the correct diameter hence 'the nearest fit to nx in size and shape'.

cheers