The Stone Roundhouse was original built as a project for George Sellios' the FSM layout. It sort of evolved into a kit of by it's own accord. The interior is fully detailed. Though the structure resembles the roundhouse on John Allen's layout, the overall design and detailing are based on Maine central and Canadian Railway prototypes. The basic structure is five stalls, with each stall occupying ten degrees of a circle. As a kit it has been built up to 18 stalls, or half of a circle with a diameter of almost five feet.
The top photo is from my diorama. The bottom photo is from The Frankin and South Manchester. Though MR magazine has featured the FSM several times, no pictures of the Roundhouse appear. We will try to post some more pics of both in the future.