Something like strips of plastic formed into sheets like blockboard.
Plastic to prevent warping due to damp conditions
Strips to allow the toothed structure in alternate blocks to be drillled
The body of the footrest also drilled precisely to allow a stainless rod to be inserted along the whole footplate in several places
Possibly covered with thin rubber matting for grip
If you don't have a pillar drill you could clamp a drill to a worksurface horizontally and add sheets of ply and blocks to make a jig giving repeatable results
I think "phenolic" actually only applies to the glue, though it seems to go with better grades. Exterior Birch ply would be fine. Some place doing cut sheets would help - I only need a couple of square feet. Double that to allow for trials. 8x4 is about £60.
Currently the surface is just smooth plastic so I guess it's not much of an issue - there are things which can be stuck on.
TBH I don't see moisture/movement being a problem, it'll live indoors.
I did think of laser-cutting thin sheets - could use fluorescent acrylic and light it up from inside with UV LEDs. It would take 75 of them at 4mm but the machine does the work. Polycarbonate would be tough as eck. This belongs in the other thread... I have access to a pillar drill but the rise is only the usual 125 or so.
The body of the footplate is supported underneath. The flaps won't be, though. The hinge is the problem if someone heavy stands on it, otherwise I think 12mm would be strong enough. any supports would get in the way once it's up, and the tubing means there's not many options to get it out of the way.
She's back from holiday now so I'll cut a single piece of 5.5 the whole width and stick 2 bits of staff bead on to see how the dims really work, and slot it on top of the existing with shock cord under, so it can come off easily. I can try things like cut through and make a gaffer-tape hinge for something to visualise.
We'll see.....
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