I used to have some custom tips for my old Westone UM3X earphones but recently went up to the 4Rs and the tips are not compatible. I got them from a Welsh company called Minerva who could not adjust them for me having recently changed their production/tooling equipment.
So the hunt is on for either acrylic of silicone custom eartips again!
I would prefer a UK based company but am willing to look elsewhere if need be.
Other suggestions also welcome!!! :)