I did my own car start to finish when I was in cub scouts over 60 years or so ago. My dad worked all the time and we didn't have any power tools so I carved it into something a little more aerodynamic than the block of wood they gave us with my blue handled scout pocketknife. And I painted it with some blue paint I found in the garage. It looked like crap and I didn't win but it was still fun. Most everybody else's cars looked a lot fancier than mine, if you know what I mean.
Raced them with my churches RA group when i was a kid. Lots of fun. I remeber the first year we went. Mine and my brother's cars didnt look that fancy. My brothers cleaned house and did good at the city meet.