This is a super rough draft version of an idea I had.
The original version of this nozzle has served me well for printing PLA, but for PETG, I needed to block the cooling on the bed. Instead of printing a new nozzle for that purpose or taping over it, I figured, why not make it adjustable.
It uses a cylinder across the nozzle with a slot in it. Turned one way, the airflow comes out for printing PLA. Turn it 90 degrees and it blocks the airflow for ABS or PETG.
I have not tested it and this is a first draft. I am hoping to clean it up and need to fix the nozzle a bit, but in theory, it would work as-is.
It is set up to print in one piece, with no supports.
If you are good with 3d design and want to run with the idea, PLEASE DO! I am sure anyone of you talented people can do better than I did. I just wanted to get the idea out there.