Metal Lines/fittings for airshocks?

I maybe wrong but in the 40 some years of playing with cars i have never seen or heard of metal airshock lines,they are all flexable due to the shocks moving as far as line you could probly use the brass tubing for oil pressure guages i'm unsure of the fittings.If the problem you are having is the lines chafeing i slip the line thru some air line tubing for aquariums and zip tie it to the frame then it is protected.