I am considering trading in my 38g (36" x 12" x 20") tank for a 20g long (30" x 12" x 12"). I would like to use the metal stand for the 38g so I thought that I could just get a piece of particle board or plywood cut to fit the top of the stand and then put the 20 long on top. There would be spare 3" on either side but my main concern would be that that stand will adequately support the smaller tank. Has anyone done anything like this before? Any unexpected results?