When I travel to other planets ( the moon only at the moment) I have to return to Earth many times for supplies. On the moon, I can make all of them ( like trees for oxygen, food, raw materials for building a moom base/city) expect for glass. Glass is a really important material for nice buildings, even in space/moon because the glass spheres with trees, farms, oxygen farms(leaves) look like very cool. I mean bulding anything need lots of glass, and thats the only material I can't make myself in the space/moon.