A professional photographer who needed a solution for 28mm technical lenses on the X-Act2 fabricated this bellows using the rear curtain bellows as a starting point.
This attaches to both the front and rear standards of the X-Act2 - the lens is mounted to the lens board which fits behind the front standard and the rear part clips into the front of the rear standard. The two standards can be brought together such that the two ends of this bellows are virtually touching since the fabric is quite thin.
Normal Rollei rear panel lens boards with bellows are Copal 1 for Rollei electronic shutters however this has been modified to Copal 0. It looks like one could change it back to Copal 1 without out too much trouble, but YMMV.
Some cosmetic marks, glue on seams showing but still working well, very pliable, and no openings seen. Did not test on X-Act2 for light tightness, however.