I built a pulk (a towable ski sled) so I could take my toddler cross-country skiing. It was easy, fun, and cost less than $25, so I put together this DYI post to share my experience:
four "O' rings
15' of parachute cord (polyrope)
plastic sled (not pictured)
two 5' lengths of 1/2" PVC pipe (not pictured)
fanny pack or other waist belt with loops to clip carabiners
Tie one end of the cord to the O ring. I used a double bowline knot, burned the end, and then wrapped it in duct tape for additional security. Thread the cord through the PVC pipe and then attached the other O ring to the other end. Repeat for the other length of pipe.
Clip two ends to the sled with carabiners, drill holes in sled if needed.
Clip other ends to your waist-belt with carabiners. Be sure to cross the two bars (like an "X") when wearing it, it makes for a smoother ride.
Fun! With this sled the pulk works best on groomed trails or thin snow pack. I dumped the boy out on rough terrain and he was less enthusiastic about getting towed after that. I plan to try attaching the poles to a more burly sled in the future and see how it goes. There are many great resources online with other designs for pulks.