A long time riding friend owns a sign shop, and has given me sheets/remnants of 3M reflective tape.
This stuff comes in track paper rolls of many different colors for a cnc cutter to make letters for truck lettering, etc.
I'm 3k miles from him now, and had to buy some from a local sign shop near me, and it was still way cheaper than buying it any other way.
That local sign shop has a $20 minimum so I got 1 ft lengths of several colors for $20, with the black being my favorite.
You can cut it to any shape up to the width of the sheet and as long as to choose to buy, and make custom inserts.
My favorite is to cut different size circles using a leather punch set, and sticking them everywhere as they are near invisible when you match the color...and applied to rims create motion when reflecting!
It's thin and flexable enough to use as a "wrap" with the heat of a hairdryer too.
just sayin'
kenstone