I once dropped a really tiny bearing ball while rebuilding a Shimano 747 clipless pedal, then spent way too much time looking, but then looked some more.

I had checked every crack in the garage floor many times, and under the flaps of a cardboard box on the chance that it might have bounced up and into the rather tall-sided box.
Again I checked that box, and a third time, but no ball.

Finally I considered that the ball may have bounced up and fallen into the corrugation along the top edges of the box's sides. I turned it upside down, tapped it, and the ball fell out into plain sight.

Never give up!

I remember sweeping my basement (workshop) floor with a magnet to find a missing small part. It might have worked if I regularly swept it, but there was too much steel dust from all my filing and so on without ever sweeping. Lesson: clean your workshop!

You boys need to get in the habit of carrying a small nut or ball bearing in a pocket, and if you happen to find yourself walking on terrazzo drop the item and don't look where it goes. Then try to find it.

That was an interwebs pic, by the way.

On a trip to the co-op a couple years ago I found three friction barcons, One early Shimano and two SunTour. No particular build in mind but you never let those things go unbought. Bagged 'em at home and eventually dug them out for something I planned to build. I had the bag resting on the edge of my desk near the workbench for a couple of weeks and noticed once or twice how close the trashcan was to the edge of that desk. The bag of shifters disappeared.

Obviously, they fell into the trashcan. Nope, I emptied it several times looking. Had a couple of builds come and go that could have used those shifters, if only I could have found them. I know I didn't throw them out but I could not find them.

I was up in the garage loft last week looking in my storage tubs for some stuff to mod a buddy's bike.

A story without an ending . . .

The ending is that I found the shifters in that tub, hence the photo. Couldn't have gotten the photo otherwise. Don't know how they got there or when, and I've been through that tub a couple of times since the shifters vanished. It's not so much a miracle as a mystery to me. I'm glad they turned up and will use them if they don't vanish again before I get the chance to use 'em.

I did get my buddy's bike fixed. Happy ending there, too.

Saturday evening, I was repairing a sander that had 4 propietary washers and lost 1 of them. Spent about 1hr sweeping my shop floor, then looking for the washer in the grass just outside the door, thinking it may have bounced there. My wife saw me crawling and asked me what was I looking for. I told her, she looked down and said "Is this it?". Of course it was.

I had a similar sort of happening after losing one of the precious Mafac gum-colored cable adjusters from a brake lever.
I was removing the cable housing from the cable and lever and the housing sprung outward to straighten itself by spring action. The adjuster flew off, hit the roof over my upstairs apartment landing, then dropped fifteen feet unseen onto a sidewalk below, and one more impact to a stop. Somewhere.
I hadn't seen it at all, everything in my memory was recorded sound and only recorded sound. I searched for over an hour, hit many spots around the planters many times each. Well, the customer was on his way to pick up his bike, I had explained what happened with his Peugeot PX10 Super Competition and I once more searched the entire area for a half hour until he arrived. He grilled me on the details and proceeded to look around, me following and saying where I had looked five times already.
Within one minute the young dude had found the plastic adjuster wheel.