SRAM owns Zipp.
SRAM has taken a company called Princeton Carbon Works to court for alleged patent infringement on the design of the scalloped inside-edge of the rim.
Therefore SRAM (or at least their lawyers) believe PCW's wheel design is infringing on SRAM's patents.
This means SRAM believe PCW's wheel is a copy or clone or otherwise duplicate of their designs.
ANSWER: PCW's wheel design is similar enough to SRAM's that legal action has begun. Thus SRAM believes PCW is another "company that makes a variable/undulating rim depth wheel" as per the title question.
More information may be found at https://www.bicycleretailer.com/industry-news/2021/03/19/sram-sues-princeton-carbon-works-patent-infringement-aero-wheels
Do be mindful of the source of news on this matter though - there appears to be bias either way in reporting.
- This post does not imply support for either party.
- This post does not comment on performance of a rim/wheel
- This post is about the form of the design, and how SRAM think PCW's wheel duplicates theirs.
- This post does not comment on the lawsuit, and simply directs the reader to another source for further information.