First chance I get I will open my kit and take some dimensions so I can look at the best way to do it.@Peter Voogt and @Dean62 these are both great ideas. Something is needed, when I did my few I was reaching inside to push and pull the frames into position which will not work so good as more frames are added. I would like to see your idea Dean, if you have the time. Maybe with some good drawings Heinrich could convince Yuanqing to include something in the kit
Depending on how much room is at the ends on the jig, it may be possible to get a board and match drill a hole in the center and one on each side of the center hole.
Add a bolt through the side of jig and thru the board, with washer in between the two, and put a nut on the outside. Then put bolt in one hole to the side.
To rotate 180 degrees, take out bolt on side, rotate and put bolt back in. Center bolt obviously always stays in place.
The two end boards would be joined by a horizontal board on each side at the bottom. Make sense?