Don't laugh.
I was working on my car, I removed what I thought was the thermostat housing on top of the block. It was not the housing but looked exactly like it.
I simply held the ratchet handle near the hole to check for clearances... the little keeper thingy on the head of ttge ratchet that looks like a washer jumped off the ratchet and fell into the engine. Craftsman ratchet, got it on my 16th birthday.
I have 3 cars so I kept trying to get the thingy out of the engine. I figured it was in the water jacket and didn't want to take out the water pump.
6 weeks later after inventing 5 different magnet tools (alloy block) I pretty much gave up.
Standing in the garage one nite, talking on the phone, just jamming welding rods with magnets taped on the ends into the engine block and low and behold, there was the thingy!
I got unlucky, then I Got lucky but....
Gotta hang in there