This is one of the coin presses once used to strike dollars from Comstock Lode silver at the Carson City mint. It has been restored to operation and they demonstrate it once a month. Nowadays it's used to strike various medallions, some of which you can buy in the gift shop.
Yesterday wasn't the operating day, but the one time we visited here (long before we moved to Nevada) we saw them operating. The press is designed in such a way that it takes two hands to activate it, which is deliberate to prevent an operator for getting his/her hands in the press, which would be very messy.
The nice thing about having a free admission to a museum near where you live is that you don't feel pressured to look at everything and read everything. We'll go back another day to look at the exhibits we missed yesterday. We also will make a point of going to the Reno museum, and probably someday the Las Vegas one, and of course we must find time to to the NSRM Boulder City as well, although unfortunately our next trip that direction is likely to be when they are not operating.