The buggy factory was built in two sections. The front rooms which contain the blacksmith shop on the first floor and the upholstery or trim shop on the second floor were built in 1882 by Robert Weirick, another Mifflinburg buggy maker. When William Heiss purchased the property in 1889, he added an L shaped addition, which expanded the factory to include a carpentry shop, a paint shop, assembly room and a drying gallery.

Like the house, the factory was electrified in 1903. Around 1908, when William’s in-laws moved into the family home, the drying gallery was renovated to become a two-room apartment. By the 1960s, the western portion of the L had deteriorated to the point where it had to be removed.

When the museum began in 1978, the factory was leaning and in danger of collapse. A restoration project was planned and implemented within the year. The northern foundation was rebuilt and support pieces were added to the interior.

The western section (of the L) was rebuilt in 1990.

In 2004, the southern foundation was rebuilt, infill lumber was installed between studs and joists were added to support the floors in several locations. The museum also “reinstalled” the original knob and tube wiring throughout the building. Visitors are able to walk through the various departments, see buggies in various stages of construction and on occasion, experience the equipment in operation.