OpenSCAD 3D printed Telequipment CT71 Curve Tracer knob prototype.

This is a prototype 3D printed knob since i don't have the original and have no idea how the original looks, but it's working for me.The aluminium insert is heated and pressed in for a tight fit.

difference(){
    difference(){
        union(){
            difference(){
                translate([0, 0, 0])cylinder(r=35/2,h=14.5,$fn=80);
                translate([0, 0, 2])cylinder(r=31/2,h=15,$fn=80);
            }
            translate([0, 0, 0])cylinder(r=15.8/2,h=10,$fn=80);
        }
        translate([0, 0, -1])cylinder(r=11/2,h=12,$fn=80);
    }

    union(){
        rotate([0,90,120]) translate([-7.5, 0, 0])cylinder(r=3.5/2,h=20,$fn=80);
        rotate([0,90,240]) translate([-7.5, 0, 0])cylinder(r=3.5/2,h=20,$fn=80);
        //rotate([0,0,240]) translate([11.9, 0, 0]) cube([6,8.5,30], true); 
    }
}