All drawings have got a 1 cm grid. I have cur the parts along the lines on the drawing with a band saw. Afterwards I have sanded smooth on the sawed sides. This has made them about 1 mm narrower than the picture shows. All parts must be adjusted before fastening to the back plate to make the balls pass freely.
The upper part of the ball track is fastened to the back plate from
behind with only one screw working as a hinge. This allows the left end
to be lifted for removal of the plexiglass tube. All other parts are glued
to the back plate. I use a small glue gun, and two droplets is enough for
each part to be glued.