I'm trying to find out what size size RHS tube to buy.

I want to have roughly 40mm O/D of one tube and either slightly smaller or slightly larger tube that fits either just inside or just outside this when painted/plated.

Anyone got some suggestions as to what sizes are easily available and fit nicely inside each other. Probably only needs to be 16/18 SWG

Thanks

This is where the steel suppliers cataloques come in handy - talk to them.

Talk to Parker steel, they have a chart which tells what fits inside what