This is an adaptor for using a MKS GEN L controller board on an Creality Ender 3.
The MKS GEN L screws to the adaptor using the original Ender 3 controller screws and the adaptor then just pushes on to the original screw mounts.
I had to drill out the small holes with a 2.5mm drill and the large holes with a 5.5mm drill.
As for fitting the MKS GEN L to an Ender 3 I had to extend the two cables for both thermistors and I had to change the end stop connectors from 2pin JST connectors to 3Pin JST connectors.
To use the original Creality GLCD use EXP1 on the MKS and EXP3 on the display, however on the display end cut the small tab on the ribbon cable plug off and rotate the connector when plugging into the display.
The big downside with this is that you can not plug in USB with the board fitted (I am going to try changing to a vertical USB B socket) and no built in SD Card.
The big advantage is that with TMC2208 drivers the printer is quiet. Also I used the E1 output to drive the hot end fan and setup Marlin to only turn this fan on when the hot end is over 50C.