Martha Stewart Living, March 2011
Working indoors, out of direct light, cut fabric to desired size. Return unused fabric to package. Pin fabric, slightly taut, to a piece of foam board.
Make sure all botanical cuttings are dry (check ends of stems), and avoid touching fabric with wet hands since water and sap spot the fabric. Arrange cuttings on fabric, pinning each (if cuttings are somewhat flat, such as ferns, you could lay Plexiglas on top instead of pinning). Use short pins without large heads, and arrange pins along cuttings to prevent casting a shadow on fabric.
Take prepared fabric outside, and lay flat in bright, direct light. Let fabric sit for the amount of time specified by fabric's directions. Timing can vary based on the strength of the sun and the season; you may wish to try a test strip first to test exposure time.
Take fabric indoors, and remove cuttings; there will be only a faint image at this point.
Rinse fabric under running water, agitating gently, until water runs clear.
Lay fabric flat, out of direct light, to dry. If using velvet, run your hand over the fabric to separate the fibers and restore the nap. Once dry, the color and contrast of the print will deepen. If you wish to iron the fabric, use a velvet ironing mat and a cool setting on the iron.
Velvet ironing mat (if using velvet)
Find pillow-sewing how-tos here. Before printing onto fabric, trim it to the shape you want for the pillow, with a few inches extra all around. This will give you more flexibility when positioning the pattern on the pillow.