hmmmm . so , why not try adapting a dome-tent, WITHOUT the flysheet
(just the inner-dome with sewn-in groundsheet)
would this be like a softbox which uses direct sunlight.
i'm thinking with regard to macro subjects/small products like you mention.
(obviously the taller/bigger the tent, then..etc). if you used a covered
table-top (w/o legs, laid on the floor), for a level, rigid base, the lighting
could look good inside what would be essentially, a translucent bag.