For my next reel design, I need a washer 5/16 inch OD, 1/8 inch ID, and .010 inch thick. I have had a similar part in past designs, and tried to make it by parting off the thin washer from a drilled rod. This is not a satisfactory method. I had trouble getting the thickness right, and the burr around the center hole was difficult to remove. The problem is that a tiny part is difficult to hold while working.
To solve the thickness problem, I have bought some .010 thick brass shim stock. I start by cutting a triangle of material using tin snips.
Here the material triangle is resting on part of the fixture in the next photo.