Building a Mini Ramp in our Garage.

We're building a small mini ramp in our garage to help us stay sane over the winter and through the dark nights. This will be used for both skateboarding and my minirocker bmx bike. Mini ramps take up more space than you think but so far it's worth it. Having a place to get a little exercise while it's raining outside or dark out has been completely worth it in my book. I spend a lot of time behind the computer editing these days, so I try to give myself a lot of different options to move around. Demensions: Total height 24inches Transition height 20.5 inches (a little short, but good for learning) Deck length 18 & 12 Inches (I'd recommend having one side 24 inches) Flat Bottom 53 Inches (feels a bit cramped, recommend longer if possible) Transition Radius 68 Inches (Happy with) Width 8ft (wouldn't want any skinnier) Length 15.3 (longest we could fit inside garage) Approximate Material list and cost (rounding up to include tax) 35 * 2x4 studs (skel