In reply to RatKing:
Hi RatKing, I had the same problem - no screws or marks on walls/paintwork allowed, so here's my solution:
https://www.flickr.com/gp/191337927@N05/U8SsbF
I cut a board to size and put felt strips on anywhere which would be in contact with the door frame. The whole thing has to be a really snug fit to prevent any sideways movement. The two 50mm x 30mm vertical supports are also cut exactly to the right length and only need a single nut each to keep them in place, since they're only coping with a vertical downward force.
The rear stabiliser is important as it clamps the board into the door frame, preventing any tipping motion.
I built the board with 3 main hold widths of 40mm, 30mm and 20mm, also cutting slopers into each strip. I use small strips of wood to reduce the depth of the 30mm edge, giving me further optional widths of (at the moment) 18mm, 15mm and 12mm.
The board's been in use since March, with great results and not a scratch on the paintwork!
Post edited at 13:55