New Nathan K5s build! Got some questions!

Ok guys I finally got the K5s from my buddy. They ended up costing me 250 but they are brand new.

So I got a friend looking into getting me a 12 gal tank and 2 compressors. He got his from a buddy for 200 bucks, and is going to see what deal the buddy will run for me.
My first question is what is the best way to paint these? I was thinking I could hand sand them and then spray them with the rustoleum bed liner in black. Anyone got any suggestions?

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