An internal servo activates a lever on the side of the device. A clever camera maker could probably rig a way to open and close the shutter with that lever. It also includes an audible tone if you're going to manually operate the shutter. There's an adjustable built in delay so you can do what's necessary before it starts timing the exposure.
You can read all about it's features and adjustments on Rudolph's website.
A key feature is that it continually moniters the light and adjusts the time if the light changes during the exposure. That means it has to be next to the camera pointing at the subject while the shutter is open. Rudolph included a rail to which the meter and a camera can be mounted side by side. I attached that to a tripod mount with my usual combination of tape and rubber bands. It is definitely heavier and clumsier than my cardboard cameras, but it wasn't all that hard to carry it in my backpack and attach it to the tripod.
I chose the Variable Cuboid using the f200 60mm front with Arista.edu 100 so exposures would be slow enough that my poor hands wouldn't introduce an error. The relatively narrow angle would also eliminate vignetting as a variable. The Arista film would reveal if reciprocity failure was included in the film data. I decided I would just rely on the meter and not fuss with compensation. I never checked it against any other meter either.
The negatives seemed be pretty well and uniformly exposed. They may look a little dense but are well within the limits for the kind of adjustment I make to the scans.
Originally built by a German fraternal society right after the fire that destroyed Oshkosh in 1875, this building has also served The Loyal Order of Moose and the AFL-CIO. When I was first figuring out the meter, I had set the f stop to 133. When I decided to use the Variable Cuboid, I forgot to change it so this picture is two stops underexposed. It's noticably thinner than the others, but still showing shadow detail.
Looking for something for the Fox Valley Photography Group's Minimalism challenge, I thought these tough little trees surviving in the asphalt corner fit the bill.