Proto Labs, Minnesota's most successful initial public offering in recent years, was the biggest market gainer Wednesday among local stocks thanks to stronger-than-expected fourth quarter 2012 results and a positive outlook for 2013.

The price of the Internet-enabled, quick-turn manufacturer of custom parts for prototyping and short-run production rose 25.8 percent to a record close of $52.82 per share. The 12-year-old Maple Plain-based company went public a year ago at $16 per share.

Fourth-quarter net income rose 129 percent to $7.4 million on revenue that rose 31 percent to $33.6 million from the year-ago quarter.

"The fourth quarter was a strong finish to a very good year, marked by record quarterly revenue and net income," CEO Brad Cleveland said. "It is particularly encouraging that each of our global operations in the United States, Europe and Japan achieved quarterly revenue records."

In a conference call with analysts, John Judd, chief financial officer, indicated that investors should not expect much higher operating profit margins than the improved margins achieved in the second half of 2012. Judd said that revenue should rise from $33.6 million in the fourth quarter to $35 million to $38 million in the first quarter of this year.

The company, which also operates in Europe and Japan, also plans more brick-and-mortar expansion.

Cleveland said Proto Labs, which employs 430 in Minnesota and 622 around the globe, plans to lease or buy more manufacturing space around the Twin Cities, in addition to plants in Maple Plain and a Rosemount facility that is not yet at capacity.

"I would expect that by the end of the second quarter all our plans will be firm," Cleveland told analysts.

Neal St. Anthony • 612-673-7144