This is extremely inspired by https://www.printables.com/model/145442-ender-3-pro-compact-tool-drawer-integrated-cable-m , unfortunately I printed that out missing that it was only for the Pro model. Since I don't have a clue about remixing models based only on the STL I redid it in Fusion while having the printed Pro version as a visual reference/inspiration.

Note: The fit is very snug on my Ender3, so if yours is slightly narrower between the 20x40 and 40x40 you will either have use a file on the left lugs on the shell or remix it. I have included an export of the Fusion 360 project, but it's a quick and poorly planned timeline, so if you adjust the width some parts of the drawer will have to be manually fixed up.

Also note that that you will have to unscrew the Y-axis tensioner and LCD mounting plate to easily slide the print into place.

• Supports should not be used.
• There are 2 version of the drawer: 
  • “long” is an exact fit to the shell depth if you are very confident about your your printers axis calibration and it's ability to produce a very flat back. For most people that is probably not the case and will result in the drawer peeking out a bit.
  • “default” is shrunken by 1% (a bit over 1mm) to allow a bit of margin.