I made myself a wooden bench for my lathe I'm going to convert to CNC. The legs are 3×4's, the top frame is 6×2 and 8×2. Everything else is from pallets. I have used it for 20 hrs and never felt it move at all. All joints are M10 studding or cross head woodscrews. There are shear panels and cross bracing. Total timber weight about 50kg. Cost 2m of M10 studding as everything else was for free.
The lathe is a Clarke CL430, about 130 kg.
If the work is well balanced, the bench material is pretty irrelevant. If the work is unbalanced, stop and put it right, you could kill yourself.
Regards
Richard.