I entered the shop with a rough build plan. However, I approached the design flexibly and altered details as I crafted. Fortunately, I had the help of Peter Brue to navigate the various tools and relatively foreign environment.
After cutting out all the pieces, I assembled the vehicle.
I then attached a large rubber band (C9 Round Resistance Band) to the rear crosspiece and wound it up about the axle.
The car did not propel forward (at least as far) as I had hoped, so I modified the design so that the band would stretch farther. I did this by switching the cross pieces, cutting a hole in the second piece, and extending the rubber band back, though the hole, and then around the axle.
Again the car did not propel forward as far I had hoped. Instead, the axle and wheels simply spun pretty much in place. I recognized two factors that likely produced this result: poor craftsmanship and lack of traction. The wheels were loosely attached to the axle, which was unevenly sanded and not itself securely in place relative to the body. Also, the relatively frictionless surface of the concrete floor freed the wooden wheels to spin in place (instead of moving forward). In an attempt to resolve both issues (craftsmanship and traction), I added rubber bands around the wheels which held them in place and added bands of traction around the surface.
The life-size wind-up car then propelled forward! However, it did not yet do so when bearing my weight.
Moving forward, I hope to figure out how to alter the vehicle so that it may move forward when a person is sitting on it. One suggestion from my peers was to use larger wheels, therefore increasing the surface area. I plan on reaching out to others with engineering and physics insight for additional input. I would also like to ease the setup. I decided to not attach the band to the axle so that, once relieved, it would not halt the vehicle nor wind up the other direction. Alternatively, by allowing the band to snap off the axle, the vehicle is able to continue propelling forward. However, currently it is difficult to feed the band through the hole and then wind it about the axle. A peer recommended I place a hook or even simple rod stopper across the rear hole so that the band would free from axle but not completely retract and thus simply require the user to stretch it the short distance from the back piece to the axle. I would also like the user to simply pedal backwards to wind it up and not have to guide the band around the axle and keep it from catching on the dowel.