Those are Avago 0603 LEDs, with the hacking done with a Dremel and a dental burr, onto an existing PCB. This is going inside one end of a machined tube test fixture; a photodetector assembly pokes into the other end to get calibrated. Haven't decided how to treat the walls of the tube; black, shiny, white?
Looks like my freehand Dremel hacking resolution is OK for 0603s, as long as no breathing is involved.
I did barely manage to carve a SOT143 circuit a few days ago, to test a transistor. A smaller burr would help, maybe.
These parts are too damned small.