Modifying theatrical scenery

The guitar is on hold while I tackle an important job. My wife is a member of an amateur dramatics group called Barton Theatre Company. They are just in the stages of moving from their old rehearsal venue of 25 years to a new, much better, venue above Smiths Restaurant.
They have a lot of scenery made from soft wood with a canvas cover for lightness. When they got to the new venue they had to negotiate a stairwell to move all their costume store and scenery store. All was OK until they got to the 5 foot wide "flats". Essentially they would go through the door but they couldn't turn them to get enough height to get them up the stairs due to the internal layout of the stairwell.
Then somebody came up with the idea of cutting them down the middle (making the flats 2 foot 6 wide by 10 feet high) and hinging them. This would mean not cutting the canvas.
I got the call "Terry can you come up with a solution?". Then next thing I knew I had a delivery of 8 flats into my shop.

My solution was to make some timber stiles that were hinged closest the canvas side. I would secure these to the existing framework using pocket screws. Then using a Japanese saw cut the timber cross-members enabling the two halves to hinge inwards. The canvas would fold face to face and this would be enough so they could manoeuvre the flat through the door and have enough room to angle them up the stairs.

I first made a hinge mortise routing jig.

Top of mortising jig.
Made from 1/2" plywood

Bottom of mortising jig

I then cut all the stiles to lengths and routed a hinge mortise either end of the stile

Hinge mortises in stiles

Next I used a pocket hole jig to cut the pocket holes on the opposite face to the hinge mortise.
I then screwed the hinges to each stile and put some waterproof membrane over the hinge. This is to stop any likelyhood of the hinges rusting and printing through the canvas.

I then screwed the stiles to the flat using pocket screws and cut the crossmembers

Stile secured to crossmember
There is a timber stiffener to keep the flat
straight (simply secured with 4 screws) to
enable transportation and stacking.

Centre joints
The black material is the waterproof membrane

Finished products (each is 5 feet x 10 feet)

My customer is happy and they can now take the scenery from my shop.