https://en.wikipedia.org/wiki/Integrating_sphere an open sourced, cheap 3D printed integrating sphere. more pics and video of it soon. matter hacker black has let me down. first part of the spool looked great, then the middle of it is a different crappy gray funky printing crap. OH WELL! i am painting the sphere anyway. the inside top of the sphere was a little droopy on the print, so i use a wood burner iron to smooth the plastic out. the iron has a V shape and works well for this. then some sandable primer and clean it up, then the finish in gloss white. you can see the LED in the one end and there will be a sensor at the other end.