I used polystyrene modeling plastic that I use to make control horns. I front of the ski can be formed with a heat gun or hair dryer and cooled over a soup can or whatever you have around. The frame is cut and glued together with hot glue, and the axle sleeve is made from a pen tube cut to length. only took about a half hour to fab up.
This is my first set I built and the do look short in length on the Bushwhacker, but I will try them out and see if I need to make adjustments. This polystyrene does slide really well and is super durable. I have used it as skid plate for the bottom of planes that belly land, takes a beating and preserves the plane