Dh built a wine cellar in our basement*. when we had to do the drywall, we had to carry each pair of sheets down the stairs, because the basement is fully underground with no walkout. I could barely carry my end on flat ground, let alone down stairs, because of the weight and there's nothing to get a grip on. Came up with what I thought was a hairbrained idea to run a truck tie-down strap under my bottom corner and carry it by the strap. It worked beautifully. Of course then later I saw (and remembered-duh) that appliance installers use that exact idea to carry heavy appliances around.
*its nothing pretentious, basically a walkin closet... With a wine chiller unit and shelves. Looks great, though!