I have simple pen tools, 'blot' brushes, randomized shape placement/sized brushes.
I tried to create a variety of brushes that each had their own vibe and would allow users to not be regulated to a single few tools.
I wanted a collection of brushes that offered their own 'flavor'.
A surprising challenge was trying to think up different types of brushes that were not just a straight line.
Once the brush's core had been made, it was just a matter of customizing them to give them their 'flavor'.
Same for the images. Once a use for a brush came to be, an idea for an image came with it.