I don't know much about snowshoes or skis, so please feel free to let me know any and all problems with this idea. It may be very short sighted ultimately. It's meant to be more of a snowshoe and only a temporary ski for gentle conditions.
Materials. 1/4 inch thick special UHMWPE plastic (IPX 2000, slightly slicker, more durable, less expansion/contraction, and more UV stable), 12 inches wide by 36 or so inches long. I'm about 5' 7" and weigh about 150 to 155 lbs–i already know it won't have a lot of control and finesse, but i'm not looking for that–just if i come upon gentle down hills etc.
Create fabric sleeve out of heavy duty woven materials. Bottom, some heavy duty nylon or polyester fabric (500 D cordura, etc) lined on the inside with silnylon (sewn together around perimeter). Top fabric also heavy duty, but less so, fabric. All sewn together in a fitted sleeve for the UHMWPE sheet, with an opening/flap at the back end that can be secured with velcro.
Flat head, pointed Titanium screws and hex lugs. Drill Ti screws at strategic places through the UHMWPE sheet. Fabric sleeve will need to have holes punched at these areas for the screws to go through. Create strapping system (this will take some definite time and thought, perhaps some less slick plastic screwed into the UHMWPE sheet, with velcro straps connected?).
In snowshoe mode, put fabric sleeve on and have the titanium screws on. Combination of strategically placed Ti screws and rough, textured bottom fabric should provide enough grip and friction.
In temporary ski mode, take sleeve off, take screws out, plug up holes with that forming silicone that is sold for ear plugs.
One immediate, probable problem: In snowshoe mode with the fabric sleeve on, and with holes for the screws to go through, snow, ice, and/or water could collect inside the fabric sleeve. Obviously the more tight and fitting the sleeve, the better.
Ultimately, it would be a lot more convenient, easier, and more durable to have something like a titanium or aluminum frame with teeth edges etc that the UHMWPE plastic could sit and get secured in, but that is beyond my MYOG abilities and know how currently. Also adds a lot more expense, especially if using titanium.
The screws method is much cheaper, easier to make, easily replaceable, and lighter. I'm estimating total cost (not including fabrics of which i have some left) to be under 150. Have no idea what the total weight will be.

