I had been digging around on my hard drive and came up with this. I ordered one about 3 years ago, so I don't know if they are still available. It was brand new and fit like a glove. Something to ask your favorite dealer about. "This was sold under the Toyo View name and is catalog number 5081. It was
distributed by Mamiya America under catalog number 180-637. Toyo Japan called this "Lens Board SGF". The size is 3 5/8" square and the hole is 1 3/8".

That makes sense. The "SGF" probably stood for Super Graphic Field. Toyo bought the tooling for the Super and made it for a few years in the late 70s to early 80s

Would these Toyo lens boards, also be 1mm. thick? And have turned down edges too?

Where the edge acts as a light seal, on the metal boards, would you need a recess on a plywood board? And what would the max. thickness to use in wood be? I would think up to 3/16" thick would work. Any advice on this?

Has anyone heard of black plastic boards, in use? Or fiberglass? Or if the molds for same even exsist?

I've used 4 ply black matte board on pacemakers with success, didn't even make a bend for the light trap. When paranoid, I do use black tape around the edges.

I think 4 ply = 1/8" thick so a 3/16" thick plywood would work if you ran a rabbet around for the light trap.

Les

I use 3/16 black acrylic, use a rotary tool with a streight cut router bit and trim the edges down to approximately 1/16 thick or to where the slide locks will just close, sand the back to rermove the gloss, and drill the mount hole. I have an Ilex #5 one one.
Charles