About this 3D model
just a thicker and inversed version of Turkey2Spartan's https://www.thingiverse.com/Turkey2Spartan/designs doing a dog tag on tinkercad is extremely easy as they have letters and numbers as set shapes and finding/making a dog tag shape is fairly simple. If you want to then add a symbol to one of the sides then all you have to do is find that symbol import it and either make it a hole or just group them together depending on whether you want it to stick out or divot the dog tag (inney vs outey)