built mine today. just like it said everything at wally-world. for like 12 bucks.. found both pencil cups near stationary, they had both silver and black. carbon in fish department, and got pair of woman's black nylons for like 75 cents. I am using two 4 inch computer fans pictured to exhaust air from my box and I threw a pic of the babies in for good measure.
**side note** at first I had twisted and doubled the nylon back to the top of the filter and secured it with the rubber band. To lessen air restriction I decided to just tie it at the base. ***not pictured