Putting together Koji's design work with Stephen's CAD, we consider the size of a test chamber for the Mariner suspension.
Koji's design uses a 6" x 6" Si optic, with an overall height of about 21.5".
Stephen's offsets suggest a true shield footprint of 14" x 14" with an overall height of 24".
With generous clearances on all sides, a test chamber with a rectangular footprint internally of about 38" x 32" with an internal height of 34" would be suitable. This scale seems similar to the Thomas Vacuum Chamber in Downs, and suggests feasibility. It will be interesting to kick off conversations with a fabricator to get a sense for this.
This exercise generated a few questions worth considering; feel welcome to add to this list!