sideway180sx

need help with making a ported box for the 18 btl i've measure the trunk space in the lincoln ls Height = 14.5 inches Depth = 24inches width = 40 inches also i will be using 3/4 inch mdf so i just need to know how much i need to cut when i head out to home depot or lowes and what size to cut for the port also what size screw should i use for the box? and material i should use. this is my first box so be easy on me.