Yes it can be made that small. You may want to do it with a nozzle smaller than the “standard” 0.4mm if it doesn’t work to good. If I were making it I would use my printer with a 0.2mm nozzle.
I would consider using ABS or PETG for strength. PLA would be ok if the washer sits flat against something like a nut where the springs pressure is uniform against the washer.
Also using PLA you would want to make sure that temps around the washer are relatively low so it won’t deform.