Does anyone make a case that holds multiple complete upper assemblies? Or something that can be used for that. I'm looking for soft sided that will carry 3 or more. Max bbl length is 16". It would be a plus to leave optics attached.

I have a bulldog discreet case. I've used it for a complete pistol on one side and an upper on the other. I have a double rifle case that has straps, but the don't really hold things secure.
I have one of the IWI cases for my X95 which had sleeves in a section that holds my conversion kits.

Any suggestions for a company that makes something along these lines? Or alternatives?

Any time “soft case” is part of the question, the answer is usually Sert TCC. You can get additional velcro straps under the accessories tab (I forget now if they come with 2 or 4 velcro straps). If all you’re using it for is uppers you could probably get by with the 30”.

Thank you both for the info, this gives me somewhere to start. I liked the Gym the most bag because of the individual pouches. It's the closest to what I'm looking for.

Really appreciate your help.

Ed