You may want to consider stainless steel....no paint or up keep ever...more money up front less money/solvents/supplies down the road....Ohsborg in Belle Plain, plenty of smaller shops in the country with good pricing. Stainless can be stick welded with the right rod, know and any welding friends the materials could be picked up at Discount Steel in Mpls with that special welding friend. No.. aluminium.... cracks at stress points over the long haul. Just my 2 cents