With a base station in a known position you can get to cm resolution with somewhat pricey but decidedly hobbyist-accessible gear: https://www.sparkfun.com/spark

With a base station in a known position you can get to cm resolution with somewhat pricey but decidedly hobbyist-accessible gear: https://www.sparkfun.com/sparkfun-gps-rtk-sma-breakout-zed-f9p-qwiic.html https://www.sparkfun.com/sparkfun-gps-rtk-sma-breakout-zed-f...