I'm building a dome with a one piece up and over shutter. Often this means losing some sky, however there are several ways around this. If you plan to mount two scopes on an altaz mount, one over the other, then by turning 12 hours in Azimuth and swinging the scopes though the fork, each scope can see (almost) all of the sky- though not at the same time. Another way is to use a hyper-hemispheric dome which allows for a bigger one piece shutter. If you are prepared to rotate the walls with the dome, then you can make even more room to park the shutter. Which method am I going to use? Why, all three, of course! Pictures will follow soon- if it works...