A PDF introducing a type of ball & socket telescope mount that doesn't have a ball called a SudiBall
A report from Chuck Lott who built the first instance after hearing of this family of designs.
The GitHub repository for this projects digital artifacts
My first SudiBall at the 2013 Oregon Star Party Walkabout (well worth looking at all the years)
Images from the 30" Baltic Birch OSP Sudiball build
An interactive wire frame rendering of a Sudiball
Fix Point Secondary
A PDF introducing a type of secondary mount that does not shift the secondary called FixPoint Secondary