drops of soft watercolor

In Motion, you can left-click on any color swatch and pop up the "System Color Picker":

For gradients, click on the color tab under the gradient tool then left-click on the color swatch displayed.

When the System color picker pops up, click on the second tab (sliders) then choose HSB Sliders from the drop down menu:

Although there are command key "shortcuts" listed in the menu, they don't work in Motion. Command - 4 will show/hide the Layers List column... even if the color picker is the "front" window.

Hi

I was working on a similar project recently, and I got some good advice here. This is the link to that thread.

Advice for creating watercolour drop effect

The advice I got was specific to my project, but I think a lot of the information in that thread will be useful for you too, as our concepts are similar.

Generally, for an ink/paint splash effect, you can apply the 'Inkbleed Heavy 01' brush style to a single bezier point.

I made a quick example for you, here is the link for that project file if you want to check it out.

https://www.dropbox.com/s/qdxd3hyrsbklhx8/Ink%20Brush%20for%20Waterpaint%20Effec t.motn?dl=0

You will need to have updated to Motion 5.4.1 to open the file.

In your Motion contents library, there is also the inkwash01 png file, which can be used to build water paint splashes with more variety, using emitters - which is the advice you will find in that thread. In that thread, you will find the advice for making the colors more painty than inky.

Fox_M was the source of all that wonderful advice, so hopefully he may respond to you with in the in-depth advice you need. In the meantime, I hope this basic information is helpful for you.