From across the pond, Instructables user AndyGadget designed a sled (or sledge) made from pvc tubing:
We have a couple of the cheap plastic sledges which are pretty fast, but not at all steerable and break easily. I wanted a sledge which was strong, steerable and fast. I chose the waste pipe to give a minimal contact area on hard snow but a larger area as the snow deepens. The tube is also slightly flexible to allow bending for the steering.
This is his second version, hence the grass in the background.