I used a standard gopro bracket and gopro tripod mount:
1) I cutoff 1 of the 3 mounting legs to fitting the bracket,
2) I screwed a small screw into the tripod mount hole (first test if the screw fit perfectly into your camera tripod mount hole),
3) I then cut off the protruding screw at 8mm length,
4) I glued a small rubber 0-ring around the protruding screw, which will hold the camera tight and in position when it’s screwed onto the tripod mount,
5) I then simply attached the whole camera mounting bracket to the Iris’s own gopro mounting bracket, with the camera facing downwards.