Small and compact and easily removeable. This mount will allow you to mount your GoPro Hero 3 to your ultimaker without the need for adhesives or screw holes. A major benifit to this mount over others is that it mounts the gopro right-side-up so the images and video don't have to be flipped. This took me 3 hours to print for all 3 pieces on normal quality.
Edit: I have added an even stronger bracket to the downloads. If you print this one, it will accept any extra screws from your ultimaker build. Thread the screws into the holes and they should press against the ultimaker frame keeping it even more secure. This is obviously optional.