This accessory is designed mainly for he DJI Phantom 4 drone but it can be used on the 3 series as well.
The idea is to have a relatively inexpensive gadget to save priceless lives. For example in the case of fires in high floor apartments or wherever the entry point is unreachable by man the drone is extremely important because not only it can break the glass of a window and then be able to tell if there is someone in danger but also help firefighters to orient themselves in a hostile situation like enclosed fires.
The gadget is very easy to assemble and most of the parts are direct fitting from 3D printing, apart from the three springs that create the energy to project the three Ø 5 millimeters stainless steel spheres ahead at once, and the main pin used to retain the trigger system and speaking of the trigger, that is all actuated remotely just tilting down the main camera by remote controls. Easy assembling and easy flying since all the accessory complete ready to fly weights just 180 grams if printed 100% infill (solid) but since that is not required the infill percentage can go down even to 30-40 % reducing the weight lower than 100 grams completely assembled.
To attach the accessory is very easy and it is done just by pulling 2 or more rubberbands accross and under the legs of the drone, also the accessory doesn't raise the drone height at landing or take off but instead it does increase his stability against wind for example because it lowers the baricenter.