I simply made the Coolest Mystery Machine Costume out of cardboard, paint, a window insulation kit, TONS of hot glue and a wagon to make it mobile! This Coolest Mystery Machine Costume didn't take very much time to make.
I attached two large cardboard boxes together and cut them to shape. I then drew the outline (lettering, flowers, lights and license plate) and painted it with acrylic paint. I then cut out the front and side windows so Scooby-Doo could "see out the window". I then used a plastic window insulation kit to create a "glass-like window". I cut circles out of cardboard to create the hubcaps and painted them, then snugly placed the creation on the wagon to create the Coolest Mystery Machine Costume!