Reddit reviews 3M Scotchcal Reflective Striping Tape, Black, .5-Inch by 50-Foot

Amazon link.

You can get reflective tape in several colors. Here's a link to a roll of black tape (reflects white):
https://www.amazon.com/3M-Scotchcal-Reflective-Striping-Black-5-Inch/dp/B00063XI64

Last summer's bike show had a vendor giving out samples of their tape - it was a matte-black finish that reflected white. I stuck the sample on my matte-black Jamis commuter and it's damn near invisible in daylight.

Bought here and took about 20 mins of some steady Xacto knife skills

You're looking for black, engineer grade/type 1 retroreflective tape.

http://reflective-tape.com/black-retro-reflective-tape/

http://www.colebrothers.com/reflective/index2.html

http://www.amazon.com/3M-Scotchcal-Reflective-Striping-5-Inch/dp/B00063XI64

http://www.amazon.com/3M-Scotchlite-Reflective-Striping-50-Foot/dp/B0010ASWF4

The amazon links aren't a great deal. You can get 150', instead of 50', of 1" tape for the same price off the other links.

I'm guessing Amazon.

This tape is black but highly reflective. It can be put all over the place without being noticed except in headlights and flash photography.

The Indiana code cited concerns red reflectors (presumably the circular ones found on vehicles) and says nothing about reflective tape. To my knowledge, no jurisdiction in the US concerns itself with what tape or decals you can and cannot place on your own clothing and vehicles.

I bought a 50-foot roll of 3M Scotchcal Reflective Striping Tape, Black, .5-Inch to apply to the rear and sides of my panniers and am very pleased with the results. It cost me $27.04 on Amazon two years ago and is now priced at $35.91.

https://www.amazon.com/gp/product/B00063XI64/

I used this for my stuff. But its thin, so itd be a pain for tracing a decal out.

There are 2 inch versions that would be easier to use. Finding the color you want might be hard. Example 1, Example 2

It looks like plain electrical tape until you shine a light on it when its dark.

3M makes black reflective tape that works well

Scotchcal: https://www.amazon.com/gp/product/B00063XI64/ (It comes in many widths and colors.)

There are black reflective strips that reflect a sort of light grey.

Here's one, there are fabric strips too.