- To create a new Brush Dynamic, click one of the Paint tools: Pencil, Paintbrush, Eraser or Airbrush. Click the Dynamics icon.
![Image](http://gimpchat.com/o/tuts/dynamics/dynamics-icon.png)
- The Dynamics list will appear and on the lower right, there is another, smaller Dynamics icon. Click that.
..........![Image](http://gimpchat.com/o/tuts/dynamics/002-dynamics-button-clicked.png)
- At the bottom of the Paint Dynamics dialog are 4 icons. Click the Create a new dynamics icon.
- The Paint Dynamics Matrix with various boxes that can be checked appears. This Dynamic will be a Random Size dynamic. Name the Dynamic. Checking the box at the intersection of Size and Random will create a Random Size dynamic.
..........![Image](http://gimpchat.com/o/tuts/dynamics/004-dynamics-mapping-matrix.png)
- Close the dialogs. Your new dynamic should be in the list.
Note: Dynamics that come packaged with Gimp can not be changed. You will find the editing window grayed out for those Dynamics.
Here is an example of using Random Size dynamics.
![Image](http://gimpchat.com/o/tuts/dynamics/005-randomsizedhearts.png)
The Gimp Manual explains the different terms in the paint dynamics matrix.
Gimp Manual - DynamicsDownload the PDF of this tutorial.