You can just spot 3 dark spots in the grooves before the epoxy starts below: These are each 1/3 of a pin (as used in sewing). I placed one into every second groove (except as you see on the right 2 next to each other, as this is a 11T gear). I positioned those 6 pin-bits with the fist thin layer of epoxy. This works exactly like reo (that is Aussie slang for steel-reinforcement in concrete). I let each layer dry for about 10 minutes and added a total of about 4 layers. Now this should be solid!