Ender-3 TL-Smoother mount replacement cover

Parts required:
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* 2x M3 6mm screws per smoother
* 4x M3 14-16mm screws
* 1x M3 20mm screw

Designed to replace the Ender's top cover to provide mounts for up to 4 TL-smoother boards, I used the ones by MKS. The smoothers are vented to allow them to dissipate heat. Because I was adding height to fit the smoothers, I also integrated a duct for the cooling fan.