Yup! i mean, i'm not doing this in a closet, but I don't have a special ventilation system either. If you feel like the fumes are making you light headed(the silicone doesn't really have fumes but it does smell a bit like fart sometimes) just open a window. When i was casting in a smaller space i always did it with the windows open and a ceiling fan on. i wore a respirator when pouring, then i left the room when i was done and waiting for the molds to set. i only cast maybe one doll a week. But like I said, i'm allergic to the liquid resin.