I've made this thing to mount flashlight and action camera to my bicycle helmet.
Used 3M double-sided ducttape and two 4mm plastic clamps to fix this on the helmet.
It is recommended to customize the bottom of this thing for your helmet shape - SolidWorks 2017 source file attached.
Simplify3D factory file attached as well (because some supports are required).
0.2mm layer / 0.4mm nozzle