A research institute that focuses on actions rather than ideas. Also: do-tank.
Like Elihu Root (1912), the first president of the Carnegie Endowment for Intertational Peace, [Jimmy] Carter heads a "non-governmental organization." (But while Carnegie is a think tank, the Carter Center is more of a do tank.)
Hendrik Hertzberg, "He's no. 19," The New Yorker, October 28, 2002
Midwest Research now ranks as one of the top not-for-profit private research facilities in the country. There are larger research institutes, but few with the growth record of MRI. Revenue for this year is expected to exceed $46 million, twice what it was just three years ago.
A science journal recently labeled MRI "a small think tank in the Midwest." Not so, says Harold M. Hubbard, MRI vice president for research. "We're a 'do-tank,' not a 'think tank."'
Scott Kraft, "Washington Dateline," The Associated Press, November 18, 1979
Do tank is the action-oriented version of a think tank (a term that dates to 1959). A not-so-surprising synonym is action tank (1987).