This is the fourth one of these I've made. The first one was similar except the platform was almost as long as the skiis. It was for a friend that is an avid ice fisherman. It had no railing around it but had tie downs every four inches around the perimeter. It's great, goes over everything and when it's time to go home just hike it up into the truck.
This one is made for a girl I work with. The deck is 18 X 30 inches and the uprights are 6 inches tall. Experience (OK drilling my five year old into a snow bank at high speed) has taught me to gusset or support the uprights laterally against fore & aft blows. The uprights are holed galvanized 1" angle iron. The supports are 1/2" flat stock.
Skiis are $3. garage sale items. The whole thing cost less that $25 and three nights in the garage.
When my son, not five anymore starts knocking out his own little deductions I'll make him one. I still have the ptototype in the attic, but his next one will look like a hardwood floor.
The box looks far forward, but the center of balance with a kid on board is directly over the center of the skiis.
If you live in an area where there's snow and need guidance feel free to ask questions. There ain't a toboggan or iron rail sled in the Country that scoots like this thing. With abrasive material or a stomp pad at the back of the ski, Dads can drag a foot to steer whilst Mom screams her lungs out at the top of the hill. 
Tip: Sprinkle sand on the wet paint to keep the chilluns from sliding out on. This thing is great if you cross-country ski.
Oh yeah, this is Bernie; named after some baseball guy. We're "watching him" as our son moved from LA to Atlanta. That was three years ago, he's in NYC and I'm ready to have Bernie see the big city again.
