I started with a pre-weighted Grand Prix body from ABC Pinewood Derby...
...I hand-sanded it for about an hour, put a coat of sanding sealer, sanded, added a second coat of sealer, sanded, then two coats of blue with sanding in between...
...I taped off the middle and painted it yellow, but clearly I need better masking tape.
What really sends this car are the decals from Indycals.com.
The wheels and axles are from Maximum Velocity. I painted the rims red with a paint pen.