cut sheets for these measurements

[mclarengts 0]

ok so I went and measured my trunk, the room I am working with is 36" wide, 20" deep, Now at the front of the box the height is 17.5" and at the rear the height is 14.5" Can anyone design me a box with 3.9cubic ft?? or where can I go to see some cut sheets of how this will look, I know it will be slanted front the front to rear.. this will be for my Fi BL 15.. thanks for all your help