Back in the day I designed and built the majority of the skateboard ramps my friends and I skated at our house. Though I had plenty of help building because what skater doesn't want to help a new skate ramp get built as quickly as possible? The crowning glory of all the ramps I built was my backyard mini (pictured), which I've written about before in this blog. It started out as a 16 foot wide, 4 foot high, 30 foot long mini, to which I later added 1 foot extensions. It probably had a 6 foot transition but I can't be sure. I used to draw transition templates free hand and just eyeball it until it looked right to me. I never worked off a plan either. It's not a hard structure to just plan as you go.