This will put it in perspective

As another representative of the thickness of .0001", figure a swipe of a green or red magic marker on a sheet of glass. Black marker is about .0002, give or take a bit.
Sam

Real-life comparisons.

Paper is about 0.003" thick

Index card about twice that (used to be 0.007").

Cigarette paper about 0.001" - depending on the brand.  Machinists would know exactly as they'd use it to indicate how close an end-mill was to the work surface.

And, when comparing to hair you need to specify what color of hair!

George

Thanks for all that info. All true.  I was just posting the illustration. It shows the outside ring as a cross section of a human hair .0035”. Compare that to the black dot representing.0001”. As small as it is, it’s a lot when having to hold a .0002” tol. It’s really a good illustration and amazing too. Go back and take a second look.

Statesrights wrote on Jan 10^th, 2025 at 6:50pm:

Early in my career I hade 100 parts 12 inches long +\- .0002. I grind them up and they sat all nite. I checked one the next morning and it was about .0003 out of tolerance. Undersized. I was in a panic. These parts were $1000.00 each. I just scrapped $100,000.00. I went and got my Forman and just in the time of telling him what I did I checked that part again and it was .0005 oversize. Letting the parts set overnight they shrank. Hold them in my hand to show my foreman they grew. He told me not to worry about it.

it may but most likely not, you only have a clearance of .00005 per side. Most likely if you are able to slip it in, it will not come back out. Any oil on either part will take up some of that clearance and reduce it to  0.  FYI I spent a huge part of my life in a precision tooling shop, the normal tolerance on the tooling I worked on was 
+/- .0002" and sometimes less. One job I had the parts were tolerance d to a stack dimension of .0005 over a stack of 10 parts. Each part was right to size but the oil on the parts from stoning off burrs made the stack oversized. That one took a bit to figure out. A good cleaning and they fell into size but am pretty sure I added a few gray hairs in the process. 
As a general rule, .0002 will give you a slight drag on a hole. If its a blind hole, air pressure will push the pin back out, a through hole, if you block the other side will give a nice "pop" when you  pull the pin out. 
Sam