I made one with flowers stamped on the bottom...colored in the grass and then cut out a bunch of butterfly stamps I had colored.  I folded them in half and attached randomly  with just a dab of hot glue.  Looks like they are flying (that 3D effect you spoke of) Another one that was fun was taking an insert from a Virginia slim cigarette box (I work in a grocery store and have to stock them---recycled stuff ) It is a wavy, rippled corrugated type thing that I sponge painted blue-green.  Added a bit of green glitter glue in Cs and it looked remarkably like the ocean.  On a curved (imaginary) line I wrote "Fair Winds and Following Seas" for a Navy friend who was being transferred.  I imagine some magazine pix of birds or small ships in the distance would have been a great touch.