EDIT: For clarification ft[sup]3[/sup] is cubic feet/ feet cubed.
I am going on this
as your sub.
Going for either a ported or vented box, to me it personally does not matter or make too much of a difference. Don't get into all the hype that ported is better then sealed or vice versa. I think this really only matters when you get deeper into audio performance and how you want the subs to handle (i.e. how you want the surrounding air to push). Subs also need to push air to work. In physics the frequencies produced by speakers have a negative wave which can cause interference when that reverse wave bounces off the back wall and into the surrounding room.
Anyway onto the box building. Kicker's recommendations for the sealed box is a minimum of 0.88 ft[sup]3[/sup] and a maximum of 2.0 ft[sup]3[/sup]. The box needs a mounting depth of 7" but we'll make it 8" for some extra room and figure the mounting surface has to be 12.5" on each side. The mounting holes are less then 12" from each other, probably near 11" or so. The actual hole you cut into the box will be smaller then 12". From this we can tell one side is 8" long and rounding up the 12.5" to 13". I know calculus can be used (optimization) to find a nice third size of the box but I usually just use plug and play for a third size. Well we don't really need to find a third size since the 13" is both the length and height. Since the area needs to be between 0.88 and 2.0 ft[sup]3[/sup] I would look for a middle number to aim for so I will choose 1.44 ft[sup]3[/sup]. Assuming we are using just a plain flat sided box the area formula is A = L x W x h. Convert everything to the same size. I'm just going to round everything into feet 13" ~ 1'; 8" ~ 0.75' gives 0.75 ft[sup]3[/sup] So we need a bigger box. A perfectly square box on all sides of 1' gives a 1 ft[sup]3[/sup] which meets the criteria. 0.75' = 9" a value close to the original 8" and 1.5" closer to around the 13" side.
1.5' x 0.75' x 1.5' = 1.69 ft[sup]3[/sup], a great number for the box.
You can really adjust any side to get the dimensions you want. Different shapes require different formulas. Here are some calculators you can play with to find volume: Subwoofer Enclosure Calculators, Fraction to Decimal, Parallel, Series, Port Length and Volume Calculators
. The main site also has some great info.
Also pick up some silicon and/or liquid nails for the building. Liquid nails makes a great way to keep the box together as well as air seals the box (very important) the silcon would be for the air sealing and not gluing.
Oh BTW I mentioned a round hole for the sub to fit. The sub is a square so it will be a smaller square hole then the actual sub. Mounting holes are 11" and 1/16".
I think I got most of it. I was typing and stepped away to eat dinner, so let me know if I missed something, skipped on something or was just vague or you'd like to hear deeper into.