craftgrrl | a puzzling question...

i gave my kids a couple puzzles for Christmas with the intent of sealing them & hanging them on the wall.

problem is...i really don't know what to use to do it. i haven't heard very good things about the glue that is made to hold puzzles together & i'm a little leery to spend the money if it's not going to work. the other option that was suggested to me was clear contact paper over the front (which i know for a fact would make the image cloudy) or over the back (which in my experience with clear contact paper... i dunno how well that would stick)

the boys' puzzles have glow in the dark places on them & my daughter's has glittery sections, so i definitely don't want to lose any of the image on the fronts...

would watered down white glue work? mod podge? when i DO find a product how exactly should i go about this?

thanks!

ETA: thanks for the suggestions! going to be heading to the store this weekend :D