rLampe = 33/2;
rLenker = 21.5/2;
dGummi = 2;
b = 15;
r = 2;
$fn = 100;

difference() {
  rotate_extrude(angle = 170, convexity = 4) {
    polygon([
      [rLampe-dGummi,b],
      [rLampe+dGummi/2,b],
      [rLampe+dGummi/2,b+r],
      [rLenker+dGummi/2,b+r],
      [rLenker+dGummi/2,b],
      [rLenker+dGummi,b],
      [rLenker+dGummi,0],
      [rLenker+dGummi/2,0],
      [rLenker+dGummi/2,-r],
      [rLampe+dGummi/2,-r],
      [rLampe+dGummi/2,0],
      [rLampe-dGummi,0],
    ]);
  };
  translate([rLampe-dGummi,-1,-r-1])
    cube([2*rLenker,2*rLenker,b+2*r+2]);
}