This is a nice brush set for your projects.
The nylon brush is great for use on plastic extrusion 3D printers hot ends. You can quickly brush away any of the debris that sticks to the nozzle while it heated.
You can also use these brushs to quickly clean up any webbing that may have occurred during the 3D printing process.
Another use is to clean out the tracks during a cnc milling project.
These little brushes are great to keep a set right next to your machine.