For the water drops motif, you will need the eponymous stencil plus pro-color paints in black and white.
First, create the water drops' background. In this case it is going to be a marbled structure. As soon as the paint has dried, pick a drop size from the stencil and place the open round shape on your painting surface. Then spray a slight gradient with transparent black on one side of the edge.
This is how the result should look like.
Then take the shadow stencil matching the drop's size and position it in a way that the area already sprayed is completely covered. With the mixture of transparent black still left in the flow cup, carefully spray over one half of the drop's edge (inner circle masking). Be careful not to evenly spray all over the opening, but create a slight gradient instead.
Here you can see the intermediate results.
Clean your airbrush and then fill it with pro-color white. Now spray over the other half of the drop's edge with white and obtain another small gradient, just as you did using black.
Now, if you carefully remove the stencil you can see the intermediate results.
With a simple sprayed point or using one of the highlight templates on your stencil, you may add a point of light to your drop of water. We wish you lots of fun creating your own drop effects.