I have been refining and assembling the cam assembly for Tarba Tron. I found a light, stiff shaft in the Milwaukee Makerspace "long stock storage hack rack"! This fortunate find likely saved me $70-$80. The steel U-channel is about 9'6" long, 4" wide, and 3" high. I tested the stiffness by placing the ends on 4x4 blocks and standing in the middle. The shaft barely flexed. I only anticipate 50 pounds of load so this''ll do! Additionally, the rectangular shape will serve well as a "key" for the cams.