I've been playing for about a week now ,and have done some minor cave exploration just to see what it's like (and have died but play with keep inventory on for now). During those expiditions, I did actually find some rusty gears just laying on the ground, rarely. However I've noticed finding some new ones in locations that I've definitely already explored and that were not there prior. Do they occasionally regenerate or "drop" in place, as if the drifters are dropping them?