Why have my paper crafts hung on the wall deformed and what can be done to prevent this? I cut these butterflies, and hands out of paper, spread gum on them and sprinkled glitter.
Then I pasted them on these CDs with Fevicol.



I did not fold them at all. They were straight the day I made them.

Deformation started the next day. I stuck the big hand's finger on wall with a tape
since that was the one that bent forward the next day. Now, after nearly 5 months all of 
the hands are deeply curved, so are the butterflies.

Sticking them to the wall has the demerit that it makes the craft immobile (I live in a 
rented house).

Why did they deform? What all choices do I have now for such future projects?
I can think of a couple reasons why your paper curled like that:


Vertically displayed paper has a tendency to curl more in my experience, especially when it has no support. 
The gum/glue itself may be causing or aggravating the curling. Some adhesives and coatings draw, or shrink inward, as they dry. (You see this in nail polish, too, when some thicker top coats cause the color to pull away from the tips.)


To counteract the curling, you could try a few things:


Coat both sides of the paper with the gum/glue, or a varnish. The drawing affect would be lessened as it would be trying to curl in both directions at once.
Tape the paper down while working and allow to dry thoroughly, leaving it overnight to 'cure' before removing the tape.
Add a stiffer material as a backing. Thin sheets of metal or wood would be the most stable. But, chipboard or even a heavy cardstock would afford some further support.