Exterior, Shed Building Type, Metal Siding Material, Shipping Container Building Type, Prefab Building Type, Flat RoofLine, and Metal Roof Material A narrow and long 8 by 40 feet empty steel shipping container in an artists’ community in San Antonio, Texas serves a playhouse, garden retreat, and guesthouse for visiting creatives.  Best Photos from 12 Prefab Guesthouses You'll Want to Put in Your Own Backyard