How do one draw refraction(and or reflection),and portraying translucency and such
Also planning blockings or frames for animation sequences in, correct realism

Also drawing things rotated, upside down, but no reference used, just memory, or techniques

Also designing action figure for sales, or just nice articulations, quick freezing materials, nonstick or mold making one can use

Finally making games in http://tululoo dot com/ but with little math and all kinds of mechanics