Just in case . . . if you're making them for a child's room, find a way to cover the length of strings on the back . . . perhaps some wide ribbon or something that could be ironed on down the edges of it.
Literally millions of roman shades have been recalled over the past year due to being a safety hazard. Sadly, a number of children have gotten their heads caught between the back side of the shade and the string, and died of strangulation. (Like if the shade was in the down position and the child tried to see out the window by putting their head behind the shade.
Just in case . . . .