Design me a Product

I have to model a product that I developed using CAD. The product is a 1-seater vehicle basically. Attached are two images. The final design should be somewhat of a hybrid between those two images. So you can use your imagination to create a hybrid design for those two existing designs. The idea is to generate a design that is as cost efficient as possible. So it uses as less material as possible. Therefore the vehicle should be relatively small overall. I am going to later prototype the CAD design using cardboard so keep that in mind when your designing it to not make the design too complicated.