About this 3D model

The box of the DJI Action 4, the outer diameter of the connection on the back is 2.2 mm, the inner diameter is 2.4 mm, and a 2 mm diameter iron rod is used to connect it. 1 yuan per meter on Taobao. The iron rod is a bit difficult to cut, be careful when cutting it so you don't cut yourself. There is an extra 1 mm gap around the inside of the box, which I plan to stick with self-adhesive velvet with backing. It's a bit like the velvet in a jewelry box. Less than 10 yuan per meter on Pinduoduo. I probably bought too little, the merchant has not shipped it for a long time.