You need to print all the parts except the "Auflage.stl" twice, this one needs to be printed 4 times.
You will need some M4 with self-securing nuts and some M3 screws and nuts and also two pieces of 10 mm rod (I used some aluminum tubing I had left). Additionally, some foam rubber so that the plane will not slip. Print some cm or inch scales (or get them from your local Swedish furniture store) and glue them on. There is a small notch in the arms which marks the 25 mm position of the scale.
Be careful not to tighten the M4 screws so that the whole assembly is able to move freely without too much friction.
You can then adjust the sliders to the intended COG from the front of the wing and balance your plane.