I made DIY custom mattress cushions for our 2014 Hawk. (I also converted the stock E-W queen to a N-S king, but that's a different issue.)
My DIY cushions are made from two plies of high density polyurethane foam. Finished mattress is 5" thick, a sandwich of 2" medium HDPU foam (glued) over 3" of firm HDPU foam. I made the cover from Sunbrella upholstery fabric. Underside of cushions is highly breathable cushion underlining fabric. Foam is wrapped in cushion wrap silk film. The large (forward) cushion lies atop a moisture prevention underlining. All materials, i.e., foam, foam glue, fabric, underliner, zippers, were purchased from Sailrite. I sewed the cushions with a Sailrite LSZ-1 machine and V-92 poly thread. I cut the foam with an electric turkey carving knife.
Sailrite videos, especially the one about cushion-making, helped. (Check it out.) I used the Sailrite method for the small cushions, but that did not work for the large cushion because of the radii on the front corners, thus I used a box cushion construction for that.
The 5" cushions are too thick to stack when the camper top is buttoned down, thus the bed must be extended when driving.
Comfort is vastly improved, nearly like our fancy expensive memory foam mattress.
Before commencing the project, I did lots of research, including buying custom foam and custom cushions, both of which quite expensive. Fortunately, I have years of sewing experience.
The full project, including the E-W queen-to-N-S king conversion, cost about $1,000. The cushion portion of the project cost roughly $700, and I have fabric left over for my bud's Fleet.
