Liteply is just using balsa as the inner layer to reduce weight. Over ten years ago I made a lampshade from ply – so thin it is see-through as well as bending into a 10 in tube. However I don’t have any details from that long ago.

Why not use two thicknesses of 1.5mm and glue together. I have done this in the past and it works well and dont forget that 3ply bends easily one way but not the other. Best of luck.

Yes it exists [unidirectional plies]

https://materialsmarket.com/building-materials/sheet-materials/plywood-sheets/flexible-plywood

MichaelG.

Or you could make your own plywood by gluing layers of veneer with the grain alternating over a former. Sounds like a lot of effort, but it might work

The “Bendy Ply” I have used is always a three ply construct with a thin & stiff centre layer, (1mm or less), which has its grain at 90 deg to the 2 outer layers. The outer layers are a a very soft straight grained timber. The grain on the concave side compresses whilst that on the convex side opens out slightly, the “spine allowing it to bend without snapping.

Two pieces will keep their shape if glued together. It bends very easily, but not compound curves of course.

It is available in, “Long Grain” or “Cross Grain”, depending on whether you want an 8ft high tube or a 4ft high tube!

You can also buy flexible MDF, basically a sheet of MDF with saw kerfs machined into it, it snaps easily, and like most kerfed timber it ends up being multi faceted, and needs sanding smooth if visible. “Bendy Ply” is much better in my experience.

If you want to make your own ply, then “constructional” veneer is available up to about 3mm thick, normal veneer is only 0.6mm. It might only be around 6 inches wide though.

Mark.

On 28 August 2025 at 14:39 Henry Buckeldee Said:

Many thanks for your replies.

I visited an auto trimmer. His first suggestion was millboard. A sample he had was quite strong, despite being only compressed paper. The intended use is on the interior. So I doubt it will suffer due to damp?

Then he managed to obtain from next door a sample of bendy or flexible plywood. This will undoubtably bend to the radius. It seems to consist of 3 layers, the inner one being very thin. I read some of these are waterproof, but the sample seems to be very soft material. I wonder if it could be varnished to give water proof properties.

Looking at the 3mm plywood I removed, it has 3 layers, the outer ones being at 90 degrees to the inner. So I do perhaps wonder now if it was bent under heat.

So things to consider.

 

All ply has an odd number of layers at 90deg to each other for balance,  so as above 3 ply will bend twice as easy in one direction than the other.

Whether it will steam is dependant on the glue, modelling birch ply was water proof last time I bought any. Most other ply is not unless bought from a very reliable source, some ‘marine’ ply is not very marine at all.

On 27 August 2025 at 20:47 parovoz Said:

Original probably steamed …..  Similar to hood hoops etc.

Think this would be the way to go, in a completely different application( false doorway arch) i found steaming ply worked pretty well,using just a humble kettle, sometimes multiple steaming applications were needed.

The ends did prove a little tricky, seemed more resistant to bending??

Two layers of the 1.5 and you won’t even need to steam, just a bit of glue between then simple hand pressure will have it follow the 6″ radius. Job done.

Thats it coat the mating faces with glue, bend to shape and leave to dry. The big advantage is that it should stay that shape when removed from the former though as you are only using two layers there may be a little spring back.

You want the grain of the central layer of each sheet running along the bend and the outer layers across the bend. That applies to both sheets. So in the end you will have 4 plys across the curve and two running with it.