Thoroughly clean the rug to remove sand and other substances. If the rug is machine washable, you can wash it that way. However, avoid using fabric softener as it will keep the paint from sticking properly. If the rug is not machine washable, vacuum thoroughly to remove particles. Make sure the rug is completely dry before moving on to step 2.
Lay the rug down on a drop cloth. Rugs are porous and the paint will seep through and ruin the floor underneath.
Create a design idea on paper. Draw a detailed sketch of your design including measurements and colors.
Tape off your design using low-tack painter's tape. You can paint the rug with checker board, stripes or an asymmetrical pattern. Secure a stencil to the rug to apply a more elaborate design.
Paint the rug using a foam brush and your first color of fabric paint. Dip the foam brush into the paint and dab lightly onto the rug. Continue adding paint until you get the depth of color you like. Step back often to evaluate your work. Allow the paint to dry completely.
Remove the tape. Tape off another section to add the second color of paint based on your design. Repeat this process until the rug is complete.