I have recently finished building a new 20x24 for instant film, and in the process, made some refinements to my studio stand. The new version is at the bottom of the page:

http://www.mammothcamera.com/mccacc.html

I make these to order, one at a time, and they're not cheap to make, but can be made to support virtually any format. Smaller stands will, of course be cheaper to make.

Please email me directly from the website with any questions.
Tracy