You are welcome to use the plans and information on the site to build your own timer using my design, but I am no longer selling timers, kits, or parts. Sorry, but I cannot provide personal support for building a timer.
The timer is an advanced design based on a picmicro microcontroller/microprocessor. When equipped with the display option, it can be used without needing a computer. With or without the displays, it can be plugged into a computer and can report race results in real time to race management software, allowing a fully computerized race that operates very smoothly. The timer is tested and supported with the excellent Grand Prix Race Manager software package. If you prefer to write your own software, all the information necessary is freely available here on the web site.
For a completely Do-It-Yourself Pinewood Derby Timer, see my DIY Pinewood Derby Digital Finish Line pages.