So I had one of these Garmin dash sand bag mounts for a 12 year old GPS that I never use and I decided to convert it to a GoPro mount. The Garmin units have a non skip rubber on the back and 4 pouches with some kind of weighted material that makes the mount excellent for non permanent mounts. Here in California it's illegal to mount anything directly to the windshield like the suction cup mounts.Sorry but I used U.S. standard screws because it's what I have on hand. Remove the old mount from the bag by the 4 screws located on the bottom. Drill them so a 4-40 bolt can pass through. Print the mount solid with 1 perimeter and 100% infill (trust me) and main block in the middle is hollow and won't use a lot of material and you need the strength. Use 4 X 4-40 screws to fasten the printed part down. The 4-40 screws I had were very long so I assembled the unit then cut them off with a Dremel so I am not sure their exact length. Finally epoxy a M5 Acorn nut into the GoPro mount socket (I like J-B Kwik for this. Be sure not to get epoxy into the threads or opening of the nut. After the epoxy sets up you are ready to go.