No problem Dave. If you decide to go with the RBF-type ribbons, then they should be around 1 mm wide, or a touch less, and about 6 to 10mm long, as an average size. They weren't anything special, just lengths of faded, coloured, cloth tape, not as 'neat and tidy' as today's variety, although, of course, at some time they would have been new, clean and bright.
Have a look at photos of parked WW2 aircraft, and you should find examples dangling, or blowing in the breeze, attached to pitot tube covers. Although there very possibly was, eventually, a 'standard' colour for armaments, almost certainly red, I've seen various colours and shades in colour and B&W photos, in red, yellow, orange (or faded red) and plain white - anything that would be visible easily - and on some pitot tubes, for example, some have been quite long, probably to aid removal.
Thin tissue paper, of the type used to cover some decal sheets, would be ideal for this; when painted, they'd resemble the cheap cotton material, and should 'drape' to whatever shape you desire.