工 pictures a carpenter's set-square or shaping tool — the prototype implement of skilled labor. The two horizontal strokes are the top and bottom edges of the ruler, joined by the vertical handle. Itself Kangxi radical #48,
工 indexes a small but high-impact family of work and craft characters:
巧 (skillful),
巨 (huge),
左 (left),
差 (difference),
项 (item).