Agree with Early B. Inert cabinets are good.
I glued 3 mm steel sheets onto the sides and top of my GR sub towers.
I used a non-hardening marine glue, with 2 mm spacers to attain a uniform glue layer.
The end result weighs around 70 kgs each, and there is barely any vibration when playing Kraftwerk...
The steel panels had been lying outside, covered in sand and acidic acid for some time (maybe a bit too long, to be honest), to give a 'natural' rusty look.
/ThePriest