Putting up a slanty canopy on a bed would be permitted as long as it doesn’t go down the side of the bed a tefach.

Chapter 315 Section 12

When you are putting up a covering on a wall, it should be done with two people, otherwise while one person is putting it up it might become an ohel.

Chapter 215 Section 13

On a large pot, if the pot is not filled to within a tefach from the top, you should not completely close it as it is making a covering.