Hello!
I successfully used 3mm Markers.
I ordered some 3M reflective Tape from Amazon and a 3mm hole puncher and made them myself.
It’s really cheap, the whole tape is only 14 bucks the hole puncher was under 10 bucks and you need small tweezers to get the backing paper off.
Works like a charm though.
In my case not. I use it on dark objects, so that could be the reason.
If you use it on white, it could be tricky for the scanner to see.
But at first place i used them on 3d printed parts (markerpyramids etc.) so i have a natural outline in black.
I can try this out on the weekend, i will let you know about the outcome.