@jyluth: I did the one you're referring to a few minutes ago. Get to the other side, fall down a bit, then grapple towadrs the direction of the ceiling. Double tap A (or X) to increase your speed (you'll need the glide upgrade) and you'll smash into the cardboard. If you check the description, you need a strong force, not necessarily the explosive gel, so slamming your body against it will work. After breaking the cardboard, it's just a matter of grabbing the trophy with the grappling hook. Hope this helps.
For the other one you're having trouble with, just try changing your angle, or perspective. Maybe look at an extensive guide. You'll need a picture if you're having trouble.