Shine through DSA keycaps.. Maybe if you know someone with a dual extrusion 3d printer and lots of patience; then perhaps shine through dsa could be a thing. The opacity wouldn't be as clear as double shot injection though. Not to my knowledge.
I have tried 3d printing caps... it is not a good result.
It is fine if you are using it as a mold, but the issue is that the caps are too brittle along the seam lines. Printing them at an angle to stagger the seam lines helps, but produces artifacts and a generally ugly appearance on the top without a lot of sanding. It's not as easy as pressing a button and waiting, get ready for some work.
However, if you are using a stereolithography or DLP 3d printer, your results would be much better. As it is, traditional 3d printers aren't really optimal for the job. However, I did print a set of low profile DSA caps to see if I could, and it worked well enough for me to realize how they actually feel to use, but they turned out to be far too bittle at the stem, and nearly all of them eventually broke. The solution isn't really to beef anything up either, there are tolerances you have to stay between, so you only can make it so thick in places and still function as intended. I suppose if you used a REALLY fine print nozzle, printed VERY slow, and printed hot, you could better fuse the layers while minimizing warp and sag. However, you would still have a lot of sanding to do regardless.
Basically what I am saying is, it is possible, but the results would be fragile and require a lot of post processing work. It probably isn't worth it.