InstaCollage Pro is an app I have on my iPhone.  I love this app!  You can make collages out of your photos.  This app has so many different styles of collages, frame options, stickers, and background colors that can be added.  This is ideally for making collages for Instagram but you can save them to your phone too.  I have even had one printed for a project I was working on.  They are so much fun and for someone who likes taking pictures and getting crafty with her pictures this app is great for me.  Now the pro edition does cost a few dollars and there is a free edition but the pro has so much more to offer,  so I feel it is worth the cost.