If you really like your composition, you can save custom layouts for reuse. The app lets you combine photos, videos, and Live Photos captured by your iPhone into a single template. You can adjust all aspects of the design including the size and color of the cell borders, frames, aspect ratio and fonts.
Diptic - which works with both photos and videos in the same collage frame - showcases your narrative across tons of templates, in categories such as Animated, Classic, Jumbo, Bordered, Fancy and Fresh.