Finally got around to designing the coupler to connect the fiber optics to connect to the light source. Pretty simple design just a 10mm hole and 15 mmm hole meeting in the middle of a tube. Planning on printing it on the ender 3.

The fiber optics ended up being about 9.5 mm wide so it should fit fine and ill put a drop of superglue to keep it in place.  To create the bundle of fibers I simply dipped an inch of it into superglue. I allowed it to harden and sliced about 10 mm off making it nice and flush.