my 300 stand is plywood , helps to start with good plywood.
its basically 2 24x48 stands set next to each other with a skin on the front.
20+years, moved to 3 homes/ its still solid. This stand and tank are a pain to move around
my other stands are all 2 inch square tube steel 1/8inch , engineered with FEA to make sure they would work in a business setting. first one was 1/4 inch tube huge mistake way too heavy, its now a stand for semi engines.
these are way easier to move around on big tanks