This is my take on the brush designed by "Makers Mashup" with some of my own thoughts on design features I thought would be helpful.
The idea of a nozzle brush was entirely new to me, but made some sense. I have experienced on more than a few occasions an errant bit of plastic dislodging from the hot end and making a guest appearance on my otherwise pristine print.
This brush helps to gently clean off the built-up plastic (once the nozzle is at operating temperature) so you can minimize the chances of unwelcome materials on your prints. This also avoids messing up your nozzle with abrasives or sharp tools... I mean, I'd never use a sharp tool to clear off the built up plastic on the hot end. [whistles innocently]
The design features I added were:
I used these felt pads available from your local giant online retailer. I strongly suspect these are a synthetic felt and will melt, but you're not going to get too many uses out of a pad before they're gummed up anyway (at least in my experience thus far).
This prints without need for supports.
My print files are sliced for PETG.
The author remixed this model.