Scales look sweet, outback!
On making washers smaller, Jerry, You were on the right track. One of those Dremel mandrels for cut-off wheels will hold the washer(s).
Run the dremel slowly against the side of a stone(Or running bench grinder stone) to grind the OD down where you want them.
Then, put them on a pin-vise one at a time to run them against the buffer before, and after doming them if you wish.