OK kindof a robot. The author still needs to move the skateboard. Anyways the bot writes out a message in chalk dust (from chalk spray) as you skate along. Me…Would be nice to automate that bit and I wish the author put a bit more info on how the spray assembly is made. It looks like the servo just pulls on the sprayer with a spring. Not positive on that.
https://www.instructables.com/id/Streettexter-Writing-Robot/