I1 — Snug fitZipcode
The winner tightened — minimal clearance, the endpiece seated flush in its socket. Diamond left, hex right.I2 — Tall shaftsZipcode
Same mate, longer rectangles descending — the sockets read as shafts coming down onto the endpieces.I3 — Flush wallsZipcode
No shoulder — the socket walls come straight down to the notch edges (|/\|), so the cut fills the full width.I4 — Loose, more exposedZipcode
Bigger clearance and wider shoulders — the endpieces sit looser in broader sockets, more of each shape showing.