Great class man! It's always great to see how other designers work with Illustrator — sort of a peek behind the curtain :) The steps are solid and easy to follow, and of course the texturing is on point. All of the more complex concepts are presented as digestible bits and approachable, definitely worth a watch.
For my vehicle, I've been on a Dune kick lately and wanted to vector out a spice harvester.
I used a somewhat limited palette and worked with global colors in order to tweak them later, and used the Color Guide panel to get complementary colors and such. Live paint makes short work of roughing everything in.
Once my textures were set and colors suitably randomized, I varied slightly from the course and made the vector patterns into brushes instead of expanded paths. The size and orientation could simply be controlled with the stroke weight and line profile. Overlapping various strokes with different blending modes helps keep thing looking unique throughout.
4. Texture Masking (Draw Inside)
To apply the textures, each color block group was duplicated to a texture layer, converted to a compound path, and the shape was set to Draw Inside. Each shape then lovingly received brush strokes with the various textured patterns.
4. Finished Details
I streamed nearly all of this illustration on my Twitch channel if anyone would like a more detailed look at the process (and some struggles :D).