Sometimes when I make things I think they're so easy I don't really have to make a tutorial. And then sometimes I hear people say, "you're so crafty" to stuff that I'm like, "really? I just dipped this piece of paper in tea and cut a heart out of the paper when it was dry!" (I mean, that doesn't really take that much?)
But then I realize that maybe other people aren't actually crafty or DIY-centred, meaning they don't look at everything and think, "I could make that" or spend their time imagining things to make. And they don't even have to be far removed from working with their hands (because most people use their hands on a daily basis for one thing or another), but somehow are far removed from the idea of making. All that to say that this curtain is really easy and doesn't need a tutorial, but a short description of what I did.
I had these white sheets given to me over a year ago. A shit tonne of them (like 8 king sized cotton sheets). And we haven't had a window cover (we have a blind) on our window since we moved in. All I did was make sure that the sheet was wide enough for our window, made sure that the "hemmed" part of the sheet was 1. open on both ends and 2. wide enough to fit our curtain rod, and then cut the curtain at a length I liked (and rip across instead of cut across).
Then I picked up some acrylic paint at the dollar store (because I had none at home), cut a new sponge we had lying around (I would have preferred to do a potato stamp but didn't have time to go buy a potato) into the triangle shape, hang the curtain on the wall with pins, and dipped the sponge in the paint and randomly pressed it (lightly) into the sheet, being careful not to get paint on the wall behind (and wiping it up right after in case I did). Then, I let it dry and hung it. I didn't hem it. I got some drips on it, and I didn't iron it. I was trying to do this on my lunch hour after all!
And then I took some horrible pictures of it because I just couldn't get a good picture. Yay for basements!