Don't let her make it.
I have two dark cloths made by former spouses. I think it's possibly a curse on the marriage. Fortunately, my - right now, and final - spouse does not sew. Not because she can't, but she (wisely) won't. I have my own old tiny portable Singer from the 1930's, and I've made cool things, including a leather hat that makes me look just like Daffy Duck. I look like Daffy Duck anyway, but the hat fills the bill - or adds the bill, take it your way.
But I don't really need a dark cloth because when L.K. Andrews - the technical guy behind Minor White's original ZS manual - was taking care of his last business, he gave me his. It's black satin on one side (inside), white on the other. That part is right. Andy had his wife make it, and she was really good - not just on the sewing machine, either. She could make anything, and grow anything to make anything out of. Go Thelma! It's great having and using a dark cloth with some history.
But Andy had one thing really wrong, so don't do this. He had Thelma sew a loop on one end that is supposed to go around the photographer's neck and attach by Velcro. Geez! No Go! Bad idea! It may have been Andy's own idea, or was it Thelma's?
What did I miss by coming too late? His home built calibrated inverse-square beam densitometer (he said he "sent it to the junk man) and his SEI meter! Bummer! I do have a whole lot of Potassium Chrome Alum, though, and some very brown Edwal Gradol. Hmmm.
My 8x10 Kodak Master View (so called by some the "Metal Deardorff") has clips on the front standard. That's a great idea. So those of you who attach Velcro to the camera mated with the opposite kind of Velcro on the cloth - you have got it just right.
I have three dark cloths, but that one is for some reason is my favorite (maybe because I like deserts and it's got the white side). Sometimes, I forget it. Then I use a sweater, or a jacket, or a copy of the National Enquirer. Not easy, that. It hurts my eyes trying to read over my head in the dark.
Take a baseball hat (or a Daffy Duck hat) just in case you forget your dark cloth.
L