Tom,
The material commonly used on ski bottoms is known as UHMW (Ultra High Molecular Weight) Plastic. The best (in my opinion, and most commonly used) thickness is 1/4 inch. This stuff is readily available in Alaska, and probably other places, but I can't tell you a supplier here. It's used a lot in food preparation, since food particles don't penetrate. Comes in sheets of varying widths, and can be rolled up, as well.
If you can't find a supplier locally or on line, get in touch with F.Atlee Dodge in Anchorage, AK. and ask them if they can send you enough of the material to put new bottoms on your skis.
You make a pattern from the ski bottoms, but make the entire perimeter extend about one to two inches beyond the actual ski bottom. Cut that pattern out of the plastic. Now, mark the side edges of the ski metal on the plastic. Put the plastic in a sheet metal brake, and brake the edges UP pretty hard. They'll rebound to about a 30 to 45 degree up angle, with reference to the bottoms. That turned up edge prevents them from hooking an edge.
Now attach the plastic to your ski bottoms. Most folks use flush rivets (heads down) but small flush head machine bolts also work fine.
Now you have a set of skis with much larger bottoms, and the plastic will help to prevent them sticking down when parked, which is a serious problem with metal bottoms.
Finally, if the skis have a center skeg, I'd remove it prior to applying the plastic, and replace it after the plastic is installed, but replace it with a one inch wide strip of UHMW. You won't have to worry much at all about the skis sticking down that way.
Then, have fun, and be careful.
MTV