I either had no idea these exist, or had forgotten about them, but these articles by Mike Kojima are pretty cool:
https://motoiq.com/karting-staying-sharp/
https://motoiq.com/pocket-size-terror-building-a-crg-icc-shifter-kart/
https://motoiq.com/go-karts-and-karting-cheap-track-day-alternative/
https://motoiq.com/project-crg-go-kart-from-basket-case-to-bitchin/
https://motoiq.com/christas-2013-ride-2013-top-kart-twister/
https://motoiq.com/pocket-size-terror-building-a-crg-icc-shifter-kart/