These US cut and sew companies can help design, prototype and manufacture your designs.

Clothier Design Source

St Paul, MN.  Apparel design, soft good engineering, product development & manufacturing located in St. Paul, MN.
http://www.clothierdesignsource.com

Monalisa Fashions, Inc

Allentown, PA.  Monalisa Fashions was founded in 1984 as a sewing subcontractor. The company has expanded into a full service CMT contractor with a 15,000 sf facility in Allentown PA. They offer cutting, sewing, packing, development, sourcing assistance, and other services for the garment industry.
https://www.monalisamfg.com/

Reuse & Baby Lou

Louisville, KY.  We offer small batch micro-manufacturing, supporting other small businesses with their soft goods needs.
www.reuseandbabylou.com