> a giant sphere covered in ~2-4 inch speakers.
There was a design floated in the late 1960s. Decades of chemicals have rotted my memory..... I need help on details.
I think there was a mention in The Whole Earth Catalog.
I think(??) that was sourced from a book about appropriate technology. The name "pasternik" is in my mind but clearly wrong. The book covered adobe housing, wood water pumps, dung-fired thermocouple radios, and other technologies appropriate in low-tech places (Africa, India, also the counter-culture).
The speaker: cut a cardboard pentagon. Mount a speaker. Fold the edges up. Do this dozens of times. Staple the edges together to form a sorta-sphere. Claims: omni-directional, stiff, low cost, horn-coupled, high performance.
> a plexiglass dome.
Obviously a good plastics-crafter with excess time can bend-up anything you can do in cardboard. And I do recall something like that (or is that the chemicals?). Likewise some wood, a tilt tablesaw, and glue can form hedra.
The convex regular polyhedra seem to stop at 20 faces (10 for a hemi), but Bucky's (and Bauersfeld's) geodesics run to approximately any number of faces.