Gopro Thumb Wheel V2
The fastener is in two parts and are just glued, they are based upon an M5x30 Lg bolt and M5 nut, (which you will need to provide)
the heads are about 3.5mm thick as a guide.
I print all my designs out on my Ultimaker 3d printer, so i know the designs work, so i would assume that the high tech shapeways printer will give even better results. All photos are of my own Ultimaker printed versions.