A stretched metal spring letting go: a fast upward twang that wobbles as it rings out, then two small bounces. Use it for cartoon reveals, a trap door, a coiled gadget snapping back, or anything that was held under tension and is now not.
twang: saw 180 Hz rising to 520 Hz over 90 ms, then falling back to 240 Hz by 400 ms (the spring recoiling past its rest point) wobble: amplitude modulated at 17 Hz, depth 0.35, so it reads as a coiled spring rather than a plain sweep body: low-pass 2400 Hz, Q 1.4, to keep the saw from being harsh bounces: two short triangle hits at 0.34 s and 0.46 s, 96 Hz and 128 Hz, 30 ms each, level 0.16 and 0.09 envelope: 2 ms attack, 300 ms decay on the twang seam: single shot, buffer 0.62 s