Late reply but....
I have one that can be bought (there are two versions that the same guys sell). But, after deciding a rebuild wasn't worth the cost, I decided to try taking my sl80 (I think?) apart. Sure enough, this air piston part was broken.
Looking online, I saw I could buy one, and since otherwise was leaning towards a bearing conversion set to run other forks in the Raven frame, I decided to experiment.
What I decided to do was drill and tap the inside of the part where the air hole once was. Tapped hole in the top, a through hole in the "base". A #8screw then goes up through the base and holds the broken threads on. I have done this part already and it seems to work. Next step is a new small o ring (that one seems to be a plumbing #6 o ring) and getting a brass screw. Then drill out the brass screw's center for the passage of the air and an o ring at the screw head just because....not really sure any leakage there would matter.
Alternatively, on mine, the thread was 7/16 coarse, so I could have drill and tapped the base for that and just put a nylon screw up the middle, maybe epoxied in. Since I have not yet finished, call this plan B.
If my break was like yours, I might have only considered plan B.
3D printing would I think be an option too, yes.