Im making jello molds and i was wondering how do get the jello out of the mold in 1 piece?

and still look like the mold with out a problem i cant seem to do it i have the jello molds seen in this picture http://cgi.ebay.com/30-HALLOWEEN-JELLO-JIGGLER-GELATIN-MOLDS-RECIPES-NEW_W0QQitemZ260300051211QQcmdZViewItem?hash=item260300051211&_trkparms=72%3A1205|39%3A1|66%3A2|65%3A12|240%3A1318&_trksid=p3286.c0.m14#ebayphotohosting