Nice work Wayne, and thanks for confirming the amber colour on the lamps.
John, for circle masks, use either a compass cutter or, for circles smaller than can be made with a cutter, various sizes of paper punch, or leather punch sets, can be used to punch out of masking tape or adhesive labels. Also, many sizes of circular self-adhesive 'price tag' labels, or those 'spots' used on wall charts, are available through retail stationary stores, which can be quite useful.
For very small circular masking, then a liquid mask or PVA is probably the answer.