I chanced upon some suitable Letraset recently, so this had to be done. A moonbase Alpha airlock sign, which is destined to go over my model room door.
Some graphic artist shop gave me 1200 Letraset sheets they were to bin. Quite a bunch are from the late '70s and early '80s.
I was lucky to get that motherload for free. It's the storage that's tricky: low humidity and low temp will keep them from flaking