Sheet of paper being put inside an envelope - fast.
Tear large envelope with clasp, slowly
Crumple large envelope with clasp
A digital effect with a pitch envelope.
Taking letter out of an envelope, unfolding it. Much paper rustling
Arpeggio with filter envelope played by a Moog synthesizer
Putting a letter into envelope. Paper movement and rustling
ATM bank machine - accepting envelope, servos intaking check.