$fn=50;
translate([0,-(8.5/2),0])union(){
difference(){
union(){
    translate([7.5,(8.5/2),0])cylinder(r=16.5, h=10);
    difference(){
        translate([0,-23.25,0])cube([3.5,17.5,10]);
        translate([0,-17,5])rotate([0,90,0])cylinder(d=3,h=8);
    }
    difference(){
        translate([0,14.25,0])cube([3.5,17.5,10]);
        translate([0,26,5])rotate([0,90,0])cylinder(d=3,h=8);
    }
}
translate([3.5,-15,0])cube([30,50,20]);
    translate([7.5,(8.5/2),0])cylinder(r=12.5, h=10);
}
}