Using propylene glycol as your paint medium allows you to add texture to your paint, or use stamps.
Simply create a heavy paste using only propylene glycol, and mix with a painting knife on a smooth surface like a piece of float glass. With a pain brush, spread this mixture flat and even. Pick up with the stamp, and stamp your piece. Here, I have used RP7852MB "strong blue." Wipe off any areas where the stamped image is unwanted. Owing to the viscous nature of the propylene glycol mixture, the stamped pattern will not be smooth, but with fun, random ripples and waves. Stamps with delicate designs should be avoided.