Does anyone know a company that could make me small quantities of a double walled tube? The first (inner) tube to be 1.5-2mm wall, clear resin with a single layer of 80gsm woven glass fibre (preferably as close to the inside of tube as possible), the outer tube to be “normal” carbon fibre with standard 1.5mm wall and the outer diameter to be 25mm.

Odd request I know...but then I did say I was the mad scientist...

I got confused by “solid tube” cos to me that sounds like a rod...I still need a void down the middle...or does solid mean opaque?

I’ve just received my square metre of 80gsm weave and more good news...light transmission and diffusion is much better than expected...Eight layers still lights up very well, and that’s without resin which I assume will only improve transmission (as doing it “dry” I’m probably losing a lot of light to internal reflections).

If I’ve got eight layers I’ve got more strength and it’s also not quite as critical that I don’t “nick” the reinforcement when cutting the design into the outer, black tube.

Is there a commercially available 20-ish mm diameter GRP tube made with about eight layers (how many mm would the wall thickness be?) of 80gsm weave? That would leave a 1.5-ish mm gap between it and the CF tube that I could fill with resin with the black translucent to lock the two together after the design is cut...which also improves the reservoir of resin available to ensure flow as opposed to trying to squeeze it through a gap that’s only the thickness of the CF tube wall.

Is there a better resin for the bonding operation if so? The tendency of the polyester to remain tacky for a long time makes it very hard to finish...

I guess at a push I could try making my own tube...but it sounds like hard work!