A player falls into a pit that is a chute into an automated mummy-wrapping machine. Player takes no falling damage, because player falls into wrapping material, but for the same reason feather fall has no effect on the result of this trap: the player is bound from head to toe in cloth wrappings and then doused in preservative chemicals.
The chemicals cause 1d8 caustic damage. The wraps cause immediate blindness (only because it covers the eyes, so this blindness is alleviated by moving the wraps away from the eyes). After 1 minute, the wraps also cause suffocation, rendering the player in an unconscious state within 1d12 rounds.
Otherwise, the player is able to move and speak as usual. If the chemicals are neutralised, the player may continue to play in a semi-mummified state, causing them to pass all disguise checks as an undead mummy.