Hi David,
How right you are! DIY is a great to get the best out of your music / equipment!
You wrote that you DIY your own Roomtunes.
What about building your own 48" Floorstanding RoomTunes or even Pressure Zone Controllers (PZC)?
Just let me know it you'd like to receive some pictures of them which show you how to build them yourself.
Believe me; they're quite simple to build;
a wooden frame with R13 isolation in it, covered in cloth,
screwed to a ground plate. That's all!
I'd be happy to provide them! :-)
Best regards,
Roy