A few buddies and I built a 2x12 sealed bass cabinet over the past few weekends. Wrapped in waxed canvas to match the head I refinished in the summer. : r/GuitarAmps
Amazon.com: Bbox Single Sealed 12 Inch Subwoofer Enclosure - Car Subwoofer Boxes & Enclosures - Premium Subwoofer Box Improves Audio Quality, Sound & Bass - Red & Black Spring Terminals - Charcoal : Electronics
Sealed enclosure explained in detail and calculator - Audio Judgement