ojinsaHi @ojinsa,
The Glaser sleeve is not available separately right now, but you can use the link @cca310 gave and submit a request for a new drop.
Because this is a handmade product in limited production, I can probably speak to the vendor about running another drop before we get 200 new requests.
I can also look into making "Case Only" an option on possible future drops of the LAMY 2000 in black and other finishes.
Thanks for asking, I'm glad you like the case and I'll do what I can to make it available.