This is a Biathlon Style Shooting Target for Air Rifles, Airsoft and Pellet Guns.
It features a mechanism, that allows the Target to swing back if its hit.
For easy replacement, the Target Plate itself is held in place by a M3 Screw, so you can just print a new plate if you happen to shoot yours into pieces ;-)
I would recommend you glue a piece of Metal Sheet on the Target Plate for better durability.
For this Project you will need one M3 Nut and one M3 Bolt with ca. 25-30mm lenght.
The 4 Holes on the Base have a diameter of 3.5mm, so you should use a Screw with 3mm Diameter.
More info and pictures tommorrow ;-)