Need to build a box. Large box

I have the

Dayton Audio TIT400C-4 15'' Titanic Mk III Subwoofer 4 Ohm
I have a ton of room for a box, I need it for a HT system. I can make the box laying down and be 8 to 10 feet long and as high as 30” or more and anything like 22” to 30” deep
Here’s the sprays of this drive

Product Specifications
Nominal Diameter15"Power Handling (RMS)800 Watts
Power Handling (max)1600 WattsImpedance
4 ohms
Frequency Response19 to 500 HzSensitivity88.7 dB 1W/1m
Voice Coil Diameter2.5"Magnet Weight136 oz.

Thiele-Small Parameters
Resonant Frequency (Fs)24.2 HzDC Resistance (Re)3.8 ohms
Voice Coil Inductance (Le)3.11 mHMechanical Q (Qms)6.75
Electromagnetic Q (Qes)0.52Total Q (Qts)0.49
Compliance Equivalent Volume (Vas)5.46 ft.³Mechanical Compliance of Suspension (Cms)0.17 mm/N
BL Product (BL)16.8 TmDiaphragm Mass Inc. Airload (Mms)253.9g
Maximum Linear Excursion (Xmax)20.5 mm
Surface Area of Cone (Sd)804.2 cm²