Best thing you can do to improve cooling is separate the hot air from the cool air.
That means dividers and ducts.
Don't be afraid of wasting some paper. Flat surfaces and square lines are easier, but round / angled pieces are not that hard.
Take the fan / cooler and wrap paper around it. If you need to change the direction cut and fit to fan / cooler. Tape and glue stick are your best friends... well razor blade and scissors too.
Just keep cutting, taping, adding pieces until its what you want... It will look terrible. Not take your cutting instrument of choice and cut it into pattern pieces. Add an extra 1/2" for joining (overlap joints glued with glue stick). Once it's all together grab our rattle can color of choice and paint with light coats. Use satin or flat paint. It's very hard to get paper to shine... and matte finish hides seams and defects better too.