STEP 5 Go to Object > Blend > Blend Options > Specified Steps > 20. Press W to use the Blend tool and click on both triangles. It should render the result immediately.
STEP 6 Try to experiment with this technique, using different kind of shapes to create unique shading in your vector-based illustrations. This is my result.
STEP 7 Open a new document in Photoshop by hitting Cmd/Ctrl + N – if you plan to get this printed later, try an A3 or A2 file with 300dpi. If you just want to experiment for this tutorial, keep it at 800 x 600px and 72dpi resolution. I always start with adding a dirty paper texture background, to give it an extra touch. Drag your work from Illustrator to your Photoshop document and Rasterize your vector layer (in the Layer menu).