I'm helping translate origami photo-diagrams. In a particular step the person must make a 45° fold (diagonal fold) with the paper. Which is the correct way of saying this "fold by 45°", "fold at 45°" or is it some other way?
I'd probably say "fold along a 45° line," but I'm not an origami expert.
If I had to translate this, I'd look at existing origami instructions in English - preferably instructions that were professionally edited or written by native English speakers - and see how they express this concept.