Pipe Audio Box

Use of OpenScad to design a vented port (a hollow cylinder) as a pipe to be inserted with x screws on a speaker audio box, at front or side of the box, adding a bass reflex feature. Then the audio box will gain or boost in low frequencies.

IMPORTANT !! The design is based upon the web "https://subbox.pro/en/"
This is a subwoofer box web based calculator.
Given the dimensions of the box, characteristics of the speaker drive, etc... the web app calculates the bass reflex pipe needed.

Variable parameters for the pipe will be :

- height of pipe
- thickness of the pipe
- pipe external diameter
- width of the support-ring
- pull-out-of-the-pipe (pootp), a portion of the pipe visible outside
- number of holes for the screws
(pull-out-of-the-pipe must not be 0, as we need the ring thickness stronger enough supporting the pipe by the x screws distributed around the ring)

The web app calculates the length of pipe (included the thickness of pootp)
So, finally, this will be t