I made these because I mounted my AMS unit upside down, made the hard to read letters even more illegible…
There are models for both orientations. The caps fit snugly but can be a little pain to remove, be careful and do not pull too hard!

Custom caps!
I have included a stp file, use the "replace with STL" tool so you dont have to fiddle with placing the letters in the right spot. 
Also feel free to upload them as a remix!