I've been working on a modular and scalable corexy design called the SolidCore for over a year now. The plan is to have a platform or ecosystem of parts that can be used on any 3d printer that uses 2020 frame extrusion. The original motor plate had a 20mm cut out to seat in the corner of the frame. One of the problems I ran into was that many of the frames use square corner brackets that don't have the clearance needed in order to mount the motor plate mount. So I'm designing a motor mount that mounts within the inside of the frame instead of on top of the frame.
For more information see https://hackaday.io/project/171316-solidcore-corexy-3d-printer