I added shelves to one of our closets in our 374ts. I was able to use a stub finder with a electrical indicator to find the aluminium studs in the wall to attatch 1x3's to the walls. I then set shelves on top and used a brad nailer to lock them in place, and a few screws to hold tight. Depending on how much room you have in your cabinets, or how much space your willing to loose? You can get a few peices of oak or pine and cut side peices to fit in, then set your self on to them and use a couple brads to hold them in. Basically a shelf with legs. You may also be able to pick up a few small metal shelf bracket pins or adjustable shelf brackets, (attatched link, and last photo). Just use a drill with a depth setter to drill the holes for the cabinet pins, a little glue on the pins, and compression will hold the shelves in place. You can buy the cabinet shelf pins, (last picture), for a dollar or two at just about any home center.