BonzaiDuck
Lifer
I've been expecting the price to be in that range. I'm having a hard time finding any of the cases you mentioned available for sale though 🙁 Maybe I'll just mount it externally to my wall because I don't like it standing there without even feet because they don't include any kind of stand, feet are available for purchase separately at that price this is ridiculous. Anyway, I didn't know about that before I bought otherwise I would've had ordered the stand/feet.
Actually, and my memory is understandably hazy after some months since I looked at the options, I thought that the "feet" or base was included. If not, your remark clarifies.
There is also an attractive fan grille or cover for the MO-RA3, so the radiator has the appearance of a bass-reflex speaker with the fabric cover so that you don't "see" the tweeters and woofers. So I still think it is quite possible to build a modified side-panel that includes the MO-RA3 into the equation.
This is all a matter of preference, confidence about tools and mistakes, cost and time. You've taken the time to put all this stuff together and test it. You may not want what I'd mentioned earlier: the sweat, the metal dust and filings, the noise and neighbors' irritation.
The only question remains: Can you design this "case expansion" so that the case looks as "pretty" and aesthetically pleasing as it did originally from the manufacturer? Possible, feasible -- a matter of planning and design. And -- troubles such as those I enumerated.