Seelye Plastics, Inc., located in Bloomington, Minnesota, began as a small plastics distribution and fabrication company in the 1950s, making PVC ductwork and plastic products for the fluid handling industry. Over time, Seelye added to its product line by including pumps, instrumentation, fiberglass grating, tanks, and a variety of engineered plastic piping components. By 1983, Seelye Plastics expanded to include a fully automated CNC machining center, including mills, lathes, and overhead routers.

Eiler Plastics began in 1932 as small material handling equipment distributor, known then as Eiler Company. By 1946, Eiler Company had become one of only a few companies in the United States chosen by plastic manufacturers to distribute plastic shapes to the public. As years progressed—and the demand for plastics increased—Eiler shifted its primary focus to engineered plastics distribution and abandoned the material handling equipment line. In 1991, Activar Inc. acquired Eiler Company and changed its name to Eiler Plastics.

Seelye Plastics and Eiler Plastics eventually merged into one entity, becoming the most diverse plastics company in the United States—specializing in distribution of engineered shapes and fluid handling components, fabrication, machining, and turnkey systems. Seelye-Eiler Plastics serves a wide variety of markets, including the semiconductor, medical, aerospace, plating and surface finishing, and water treatment industries.