Materials: sharpies, basic acrylic paint, small/medium paintbrush, big mop paintbrush or stencil brush. 1/8 inch cast plexiglass sheet. Acetone/alcohol for cleaning the plate to start and fixing mistakes.
Step 1: Using a photo underneath the plexi as a guide, use a sharpie to delineate features you care about. It's most effective to vary the drawing technique here, using outlines, stippling, hatching/cross-hatching, cross-contour lines, etc. And filling in solid areas, though I didn't really like the way that turned out for this photo-base; it was very effective on some of the garden pieces other people did, though.
(Mountain photo provided by teacher)
2 and 3. Flip the plexi over; paint goes on the non-sharpie side. Have the photo to the side as a reference, Using a wet brush lay in some loose, thin washes. Avoid portions that should be fully white. It should be wet but not full on runny; dab off excess with paper towl if necessary. Then, while still damp, use a toothbrush to spatter undiluted/slightly diluted paint to add texture.
4. Block in any parts you want to be fully opaque/bright highlights. (This is where I messed up,.) You can have lots of empty space still at the end of this phase (in other words, I should have left the sky blank, but I didn't understand what was coming next.) You don't need to follow your outline exactly if you don't want, this is a very loose style.
5. Using a big brush, cover the back in dabs -- like how you use a stencil brush -- to bring the piece to fully opaque, and add background color and texture. This is what the back looked like when complete (which I almost like better than the front, lol.)
6. The finished piece. I like the mountain with the stippling, and the bottom with the darker valleys, I don't like the streaks in the sky, and pretty much anything laid in with the larger sharpie, particularly the solid places. It's hard to see straight on, but the separation between the drawing on the front of the plexi against the painting on the back adds a nice depth.
When/if I do this for my own work, I'll probably do paint/ink on both sides rather than sharpie, or sharpie only very sparingly. (Of course, anything I paint is likely to finish with a largely black background anyway. And I'll seal the front with a glossy arclyic varnish for my own peace of mind.