The MMU3 comes with 5 sets of injection-molded spool-holders, the (also injection-molded) connectors that are part of the package are designed for a circular arrangement which requires quite a lot of space - it e.g. doesn't really fit on top of the original prusa enclosure.
This design consists of a new straight connection-bar that can be printed on an MK4. It is therefore split in two pieces that fit the MK4 print-bed. Both pieces are being connected with a wider PTFE-holder-connector.
The author remixed this model.
the connector that connects the two pieces of the connection-bar was created from scratch, it is inspired by the design of the ‘MMU3 printable parts PTFE-holder’.