Yeah mylar or poly. either one will be your light proofing.
It's all in how you put it together. If it's properly made you can leave it in your room or where ever you want to. lol
But remember it's not smell proof like a tent would be. but cost wise it's worth it.
I called walmarts customer service line to find out the weight limit of the hanging bar "For my heavy clothes, I don't want the bar to fall down" lol
it can hold up to 50lbs. "according to their records"
ANYWAYS, i have to head out for a bit. I'll be back