Sorry about the delayed response to the follow up question. By having a bundle of straws with the bundle sized to fit the port, they when pushed in, the outside diameter of the port holds them securely in place. The bundle is round, with tape only around the outer perimeter. This is really a two person job, one holds the bundle in the round position and the other tapes around them.
Once the tape is applied, you can push the straws that aren't taped, ie. those toward the center versus the outer layer either in or out (so to speak). Since the bundle of straws are only held in due to the tight fit, you can easily pull the whole bunch out from the port at any time and may find it easier then adjusting how many straws are pulled out or pushed in.
Imagine holding a bunch of straws clamped in your hand. Your hand only comes into contact with the outer layer. The inner layers can be slid in/out while still holding onto the outer layer.
I hope this is clear. You may find that standard straws are longer than you want, but you can always cut them down to different lengths. There is actually a speaker manufacturer that provides such a device for tuning their port - I don't remember the brand and I am sure they use something that at least looks nicer than drinking straws.
This approach does not "close" the port making a sealed design. It does reduce the total opening and the way the air interacts to some degree. There are lots of speaker mfgs. that offer partial port inserts for tuning (my Gemme's and Wilson speakers are two examples of companies that do this). The straws have a similar affect, but actually provide for more variability than just a simple insert that reduces the diameter of the outlet.
