Case Study: OK Foundry & Oswalds Mill Audio

HPI Case Study

Client: OK Foundry, Richmond VA 
End User: Oswalds Mill Audio
Product: Cast Iron Open Baffle Loudspeaker


OK Foundry, an iron foundry based in Richmond VA well known for their architectural castings, was recently involved in creating a very unusual end product: a large, freestanding open baffle speakers made of gray iron. The dimensions for this one-of-a-kind set of speakers were 34.6″ x 51.1″ x 3″ each and weigh around 330 pounds each.  

OK Foundry’s client, Oswalds Mill Audio (ΩMA), is a unique audio company based in DUMBO, Brooklyn. Their design philosophy states, “Instead of following current trends and embracing so called ‘cutting edge technology’ we take a look back.” All of their hand made audio equipment is made in Pennsylvania out of local hardwoods, slate and steel. In addition to their extremely high-end products having a retro appearance to them, they also embrace audio fidelity concepts used in cinemas and studios in the 1930’s through the 1950’s.

ΩMA had created a design for a large open baffle loudspeaker system cast from iron. Because of the complexity of the design, the foundry determined that the 3D sand mold made more sense than the price for tooling for essentially a “one-off” casting. Also, the tooling to extract the mold would have compromised the design and because HPI was able to print the right and left sand molds there was no need to individually tool the same set.


HPI created the complex mold utilizing our ExOne® 3D Sand Printer and OK Foundry was able to pour and create a remarkable product which will be on display at the International Contemporary Furniture Fair, May 17th-20th at New York City’s Jacob Javits Convention Center.

Photographer Cynthia van Elk has provided some photos capturing the whole process of creating the speaker from sand mold to end product.

HPI takes pride in being able to provide a wide range of solutions to complex design issues facing foundries and fabricators today.