The Yupard triple "soup can with-a-handle" light also has the same threaded shelf for the LED's, but it has the 3 separate conventional stars, 16mm's, details here: https://budgetlightforum.com/t/-/23130, post #16 has a picture of the shelf/emitter plate.
Ouchy is doin a great job on on the heat sinking of that light, little different direction from you (OL) on this one, but close. He credits you of course for the tips/methods 
.
Those copper discs look great! Do you mind posting the source, if they would sell similar small qtys?