Proto Labs Inc. said Thursday that it has bought a manufacturing facility in Plymouth that will employ 350 workers and open next spring.

The Maple Plain-based company, which makes custom parts and prototypes for a variety of customers, will spend $15 million to buy and renovate the Plymouth Industrial Building on Niagara Lane. Proto Labs also plans to hire at least 100 new workers for the plant and move some its existing workers from Maple Plain to Plymouth.

The new building "will help facilitate the continued successful growth of our business," said CEO Brad Cleveland. The plant "will be our fifth building at three different locations in the Twin Cities area." Proto Labs has 500 employees in Minnesota and 200 in other locations around the globe.

While the firm's $15 million investment is comparatively small, it is another indication that Minnesota's construction and manufacturing sector is making a comeback since the recession. Proto Labs, which reached $143 million in annual revenues in 2012, enjoyed a 28 percent jump in revenues during the first half of this year. It now needs more space to accommodate its growth, officials said. The site, a former die casting shop, will also house the company's Firstcut injection molding machines.

Other expansion projects underway in the state include the $30 million expansion of Viracon's building glass factory in Owatonna, 3M Company's $150 million R&D lab in Maplewood and AGCO's $42 million expansion of its tractor plant in Jackson.

Additional projects brewing include Toro's pending expansion of its Bloomington headquarters and DataCard's plans to buy and renovate the TE Connectivity building in Shakopee for $30 million.

Separately, Schwing America confirmed this month that its Chinese owners are considering Minnesota for a second factory. Schwing currently makes concrete pumps and other equipment for the construction industry in White Bear Township.