Ed Huntress wrote:

have long, thin tubes loaded in compression. Aluminum could help,
theoretically.

How, Ed? Long thin tubes approach the Euler formula in which only
elastic modulus and radius of gyration matter. For example

2{pick}S_r I_tube 2 .05 {rem} radius of gyration for 2"OD, .05"
wall
0.6896557112
2{pick}S_r I_tube 2 .15 {rem} radius of gyration for 2"OD, .15"
wall
0.6562202374

Not much change there but the equal weight .05" wall steel tube would
have three times the elastic modulus of the .15" aluminum tube and, in
fact, a slightly larger radius of gyration.

Ted