The U.S. Army Corps of Engineers (USACE), St. Louis District, is seeking businesses that are interested in and capable of fabricating a physical, 3D-printed model of the Lock and Dam 25 New 1200-ft Lo... The U.S. Army Corps of Engineers (USACE), St. Louis District, is seeking businesses that are interested in and capable of fabricating a physical, 3D-printed model of the Lock and Dam 25 New 1200-ft Lock Project. The model will serve as a key communication and outreach tool for both technical and non-technical stakeholders.