Roundels
Further to earlier threads our Air Cadet Sqn has just restored our Meteor NF14 gate guard and we asked this question. We visited the Restoration Centre at Cosford who showed us they use a pair of compasses to draw the circles then apply narrow ( 6 mm ) nylon marking tape along the lines, as it follows the curve. Then broader masking tape is applied to the waste side of the nylon tape to give a broader protection boundery when applying paint etc.
They also gave us the codes for the correct shades of red white and blue.
Neeless to say I am glad we were only applying RAF markings !!!