I haven't gotten around to entering the 2015 prize competition yet. So, I assume maybe the April 3 link on the blog might be a subtle suggestion. So, OK, we'll try again for 2015.
Using transparent plastic or glass filament (in a clear epoxy matix), BuckyBot SHOULD be able to make a transparent/translucent dome and make a greenhouse.
We've already explored solar distillation: Build a translucent dome over a salt lake/shallow bay. Sunlight warms up the water under the dome -- increasing humidity. At night, the dome inside surface will collect dew, which runs down the underside to the base of the dome. Fresh water from salt water! Catch basins around the base collect and hold the H2O.