Painted sidepanels. I added a blowhole to the top panel and the back panel since there was a hole beside the motherboard.
I also used a hammered finish black spray paint. Turned out awsome because its glossy.
before cutting the blow holes and painting
after cutting the fan holes and painting
I just applied a nice coat of thermal paste with a painting palette knife.
This tool works great for getting an even coat.
Final painted window
Here is the gif I found on an airbourne website.
I just traced it in CAD and printed out on two 8x11 pieces of paper