
My pop-ups won't stay straight
Every time I try to make a shape that needs to have a straight wall folded in the middle so that it can become flat, the wall doesn't stay flat when I prop it up (as shown in the image).
I'm only doing some tests, so I'm using 75 g/m² paper. Am I doing something wrong? Is it just the quality of the paper? Is there a trick to fix this?
Thank you in advance!