I'm interested in creating a storage area for lump, racks, etc., too. This summer I'm building a smoke shack with removable sides for winter/summer cooking. I was thinking of using an old gas grill cart and building a storage area under it but after seeing swamprb's post I have to agree, it's already too small. I like materials like wood and metal. I'm going to keep my eyes open in places like the Restore of Habitat for Humanity, sometimes they have really cool things for sale. I've seen old metal lockers for sale, too, sometimes in groups or three or four. Sure would hold a lot of lump and stuff.
Holds 3 10 lb. bags of lump, a 20 lb. propane bottle, a Big Easy turkey fryer, cooking grids and pizza stones... as well as an 18 gal. storage tub for smaller stuff. Strong enough for 3 to sit. (I'm 270). Weathertight.