If you mean that you want to make a washer that is 0.010" thick then you can use a shim punch and punch yourself a 0.010" washer out of 0.010" shim stock. If you are wanting to machine an existing washer (i.e. the o.d. or i.d) then you could put it on a bolt and run a nut up to hold it tight and then machien the OD. The ID is harder to do, maybe you could sandwich it between two peices of aluminum and then drill thru the whole thing?