puck_diameter = 95;
puck_thickness = 4;

cutout_l = 80;
cutout_w = 30;
cutout_d = 2;
difference(){
cylinder(h = puck_thickness, d=puck_diameter, center=true, $fn=360);
translate([0,0,(puck_thickness-cutout_d)/2])
cube([cutout_l, cutout_w, cutout_d], center=true);
}