Washers for the inside at the pivot, or washers for the outside to hold the scales together?
For the inside washers: Tower Hobbies has some 8.5 x 11 sheets of thin plastic that works good for spacing washers and for friction control of the blade as it rotates against the scales. The stuff is less than half a mil thick and comes in a couple different colors. Use leather punches for whatever diameter you want to use to make the washers. I like 3/16. Put a 1/16 hole in the center with a makeshift punch on an individual basis for each washer or drill several at a time as they build up inside of the leather punch by making a dozen at a time.
The makeshift punch can be made by grinding a flat spot on a slight angle at the non-business end of a 1/16 inch drill bit. Put it in your drill press upside down and match it up to a 1/16 hole you have previously drilled in a piece of steel. Place the plastic disc over the hole, press the drill bit through the plastic into the hole in the block and bingo - a washer is made. This can also work with shim material of thin brass. Make sure the hole is deep enough in the lower block to make several washers before having to drill out the hole to remove the plastic plugs or brass plugs.
For outside washers: Use the #0 brass or stainless washers that are .125 OD, .065 ID. You can get larger dia washers also to stack them to achieve the bullseye look. The size #00 can also be incorporated into use for the bullseye washers or just as a lone washer. However, if used by themselves, be careful peening them because you will easily embed the washer in softer scale material during the process. Also, the inside diameter for the #00 is around .055 as I recall and you would have to ream the hole out to a minimum of .062 to use 1/16 rod. A #51 drill bit works if I remember correctly. You can also order 1/16 nickel silver rod to go with the stainless #0 washers if you don't want yellow for pins. Nickel silver is merely white brass to simplify the nomenclature.