I got a hard time finding valuable information on speaker building on the internet. It's a very complex art and there's a factor of luck and randomness as you can't control all of the parameters. I've chosen to make a sealed enclosure, so I would save the trouble of trying to tune the box and vents. Sealed enclosures tend to give less sound output than properly vented enclosures, but are alot simpler to design and build.
The internal volume of the box, measured in liters or cubic feet, is a critical factor in the design. Speaker manufacturers provide the VAS, which is the equivalent volume of air the box should contain. You can find a couple of calculators or formulas to get the exact volume your box should have, depending on the driver type, box type (sealed or vented), the resonant frequency of the driver and other parameters. To be honest, I didn't even follow these rules, my box being a little under the calculated volume. I did noticed that if your make a sealed box, you really need to get it sealed properly to get the right sound. In fact, my subwoofer sounded awful until I installed the backplate to seal the box. The other tip I followed was to add an internal structural piece to prevent the box side panels from warping under the pressure. If you simply create a square box without any internal structure, your box might wobble and sound ugly.
Below are the CAD drawings made to see if everything would fit together and to provide the cutting patterns for the CNC.