Based on other ideas, this is a project to create a modular machine to be used for drawing texts on the floor.
https://github.com/amirv/waterwriter
First design is to use something like that:
Inside it there will be a pressure tank like this (or two of them):
And a micro-controller to control 8 valves and a rotary encoder.
Using the rotary encoder which count the wheel rotations the micro-controller can sense the distance the cart moved.
According to the distance and text fed to the micro, 8 valves will be timed to print the text on the ground.
The painting module should be modular, and can paint using water, paint or sand.
See for example this:
The valves could be bought, like this:
Or printed like here:
Another nice option for a valve using a servo here:
Some links:
https://www.thingiverse.com/thing:2253252
https://www.thingiverse.com/thing:3307864 :
The author marked this model as their own original creation.