Have a look at this race track, made from an IKEA packaging cardboard box and two shoe boxes.
We used scotch tape and staplers for the assembly of the boxes. We haven’t had a plan, but this led to a lot of improvements during the implementation of the idea.
We used also wooden ice cream sticks to separate the two lanes. Thus each car has its own lane and there are no accidents.
We applied PVC electrical tape to make the track faster.
We also made a parking lot for the cars.
The end of the track is closed, so there’s no need to gather all the cars at the end of the racing.