NO
You can NOT replace an arch with a corner therefore you can NOT have 4 square corners on a MAS-570™. The arches are the key structural components of the MAS™ system.
There are NO round corners on any MAS™ structure. It may be possible to perform a faux “rounding” of the two square corners on the exterior. A interior finish crew may be able to perform a faux “rounding” of the interior of these same two square corners.
It possible that you are confusing the ARCHES with a round corner.
If you want a MAS™ system with 4 corners please consider the MAS-1300™.
AUG