The Blueprint Finder is a HUD designated at the bottom left hand corner of the screen and as the name suggests, finds blueprints by using a arrow that points in the general direction. As you get closer to a blueprint, the arrow begins to spin, and as you get progressively closer, it spins faster and faster.
The Blueprint Finder can be turned off in the options menu in case you want to find them yourself or if you have found all Blueprints. That makes it useless due to the fact that the slot for it will still take up some of the space on the screen.
Blueprints and the Blueprint Finder don't appear on Creative Mode, however the block used in Blueprint Finder, the blue box, is in Creative Mode but it doesn't activate the blue print finder nor does it spawn Blueprints. Blueprints can only be seen in Dig Deep.