I made a cooling cover that takes a USB-powered 80mm fan to actively cool a DEC740/750. Please enjoy as you will, all descriptions are in the links below.

https://makerworld.com/en/models/147498#profileId-160928
https://makerworld.com/en/models/147423#profileId-160862

https://makerworld.com/en/models/147498#profileId-160928
https://makerworld.com/en/models/147423#profileId-160862