Run a strip of low-tack tape around the walls and ceiling next to the edge of the accent wall. Protect the baseboard under the accent wall with tape, and place a drop cloth in front of the wall.
Spray the back of the houndstooth stencil with a thin film of spray adhesive. Wave it around for a few seconds to help the adhesive dry to a slightly sticky finish. Place the stencil in position in the upper left corner of the wall, and press it to adhere it to the wall.
Pour a small amount of latex paint into a paint pan. Dip a foam roller into the paint. Run the roller back and forth in the pan to cover the roller with a thin, even film of paint.
Roll the foam roller over the houndstooth stencil. The roller will deposit paint in any open area of the stencil. Roll in both a horizontal and a vertical direction for even coverage. Do not roll beyond the outer edge of the stencil.
Place the roller back in the pan. Remove the stencil from the wall. Wipe off paint on the back of the stencil, if there is any, with a damp rag.
Reposition the houndstooth design. Work vertically or horizontally, depending on your preference. Match it up with the last design using the stencil's registration marks to help position it.
Roll on the next stenciled image. Continue stenciling until the accent wall is covered in a houndstooth design.
Make any touch-ups with a small paintbrush.