Sheer silliness here, but I hope some readers will be amused. Quite a few bike-related items here. Maybe another good title would be "STP."
This was good practice too: drawing all those compound shapes, none of which were lined up in the same plane, and trying not to get so stuck that the drawing lost all it energy.
That object with the dial and knurled valves is, ironically, the regulator from my old airbrush compressor. Haven't used that for its original purpose for a long time - we use our compressors (we have two) for cleaning delicate photographic equipment, and blowing up bike tires.