These photos are samples of the 1/24 slot car kits available from Fein Design Modell in Germany...
This is Jörg Stephan's beautifully built Chaparral M12 model. He refined the engine with many additional lines and connections, which are not included in the kit.
Here is an excellent Honker model built by Hans Tschudin in Switzerland.
Jörg Stephan shows us his great Porsche 917-PA. To allow us to marvel at the tiny engine injectors machined in brass, he designed the two removable covers! The nozzle at the head end is milled with the hexagonal wrench size of 0.7 mm, and a hole for inserting the fuel lines. The straps for securing the caps are made of real leather of course!
You can see more customer built models here: http://www.fein-design-modell.de/html/fein-design-modell.html