MAYBE SPOILER

For the last problem you can bend the sheet such as the two arrows point in to the same direction(up) and are in the same side, that is a rectangle. On the side of the arrows(left of the rectangle), the bottom half is an arrow pointing up and the upper half is an arrow also pointing up.

Then you bend the paper such that the lower side meets the center and the wrap around the upper side around the previous bend. I got a cilinder