as headline says, its must have. this putty is easy to use, easy to shape, cut or sand when its dry. ive used it for plastic and wood model kits as well as for diecast models repair and never disappointed me. when shape is dried, its quite strong and not so easy to break. youll probably have to use rotary tool to sand it or shape it after its dried. There are few different types of it. in this case, its Miliput black. Its the most versatile putty of all other ones. You can make both big and small shapes, use it in plastic cast and its fine grained so it will make good final product. However, for extremely small parts, id suggest to get Miliput white or ultra fine.