Radius = 0.5;
Hoehe = 1.3;
Phase = 0.1;
Basisdicke = 0.2;
Basisextra = 0.2;
Bohrung = 0.25;
Schluesselweite = 8;

difference() {
    translate([0,0,-Hoehe/2])rotate_extrude($fn = 100) {
        polygon(points = [
            [0,-Basisdicke], [Radius+Basisextra,-Basisdicke], [Radius+Basisextra,0], [Radius,0], [Radius,0], [Radius, Hoehe - Phase], [Radius - Phase, Hoehe], [0, Hoehe]
        ]);
    };
    translate([-.0,0,0])rotate([0,90,0]) {
        translate([0,0,-.5])linear_extrude(.5)circle(r = Schluesselweite/10/sqrt(3), $fn = 6);
        cylinder(h = 1.6, r = Bohrung, $fn = 100);
    }
    rotate([0,90,0])cylinder(h = 4*Radius, r = Bohrung, center = true, $fn = 100);
    translate([Radius,-Radius-Basisextra,-Hoehe/2-2*Basisdicke])cube(size = 2*(Radius+Basisextra+Basisdicke));
}