I often used my vacuum cleaner (Karcher A2004) to clean dusts from fan grills. Most of the time it worked, until I came across a fan with very fine grills, in which the dust bunnies would stuck at the grill and I would need to poke it with something. It's getting annoying at times, so I decided to make my own homemade airflow straightener.  It allows air to flow in greater force in straight direction. This is achieved by using small pipes, or in this case drinking straws, to split the airflow into several smaller channels at the opening.

What you need:
- Paper core or PVC pipe
- Lots of drinking straws
- Scissors / penknife and ruler

Putting it together:
First you need to get a paper core (from kitchen paper, sticker rolls, etc) or PVC pipe that fits into your intended items. I have plenty of paper cores and was lucky enough to find two that fits my vacuum tip and subwoofer port. Measure the length of the core, and cut off uneven surfaces. Gather all your drinking straws and cut all of them according to your core length (Pic 3). You are free to use any straws, but I personally recommend using IKEA SODA straws (Pic 2) because they are relatively thicker than those straws you get at McDonalds :). Stuffs more and more straws into the paper core until they are tight and hard to slide in either directions (Pic 4). When the straws are in place, you're done! (Pic 5)

Result:
Now you can use your DIY Homemade airflow straightener for small fans, vacuum cleaners or even subwoofer! As posted on my previous Instructables, I used one of these for my bathroom subwoofer (Pic 7, 8) to reduce port noise. It works, although it requires quite a bit of patience for trial-and-error to find which length works best to reduce port noise. Also, my vacuum cleaner now has better close-up vacuuming capability (Pic 6).