What would one make new transmission lines out of? I cannot find brake tube big enough.

I have thought of:

Copper tubing?

Hydraulic hose?

Steel tube? that i cannot find anywhere

I have all the stuff to bend the tube and flare it, its just finding the larger tube and related fittings that given me the problem. I know what screws into the trans end of the lines are pipe thread fittings, but not sure of the other end

Thanks in advance

 

steel be my first choice, its usually avalible at metal shops.