Sunlu S4 Er3 Fan Error Vent Fix

For anyone that is getting the Er3 error on their Sunlu S4, this is how I fixed it. 

The Er3 happens because of a design flaw in the S4.  Once the chamber is up to temp, the cooling fan on the heater element is not able to cool the heater sufficiently.  I feel this is because there is no way to exhaust the fan to ambient air.  The fan tries to dump the heat back into the chamber, and this does not cool the heater element fast enough. The only fix I've seen so far is to add spacers and open up the whole bottom of the unit.  The issue with this is it lets in more humidity and makes the whole thing louder.  

My solution is to drill a 60mm hole in the bottom of the case in line with the radial axis of the fan, then I printed this cover that locates in the hole.  Then match drill holes for the 3mm screws.  Hold in place with nuts on the back side.

I'm also including the step file if anyone want's to mod the part.