$fn = 60;

module base()
{
    difference()
    {
        square([146, 101.5]);

//        translate([0, 101.5/2]) circle(48.5/2);
//        translate([146, 101.5/2]) circle(48.5/2);

        translate([3.3+68/2, 7.75 - 27.5/2]) circle(27.5/2);
        translate([3.3+68+3.4+68/2, 7.75 - 27.5/2]) circle(27.5/2);

        translate([3.3+68/2, 101.5 - 7.75 + 27.5/2]) circle(27.5/2);
        translate([3.3+68+3.4+68/2, 101.5 - 7.75 + 27.5/2]) circle(27.5/2);
    }
}

minkowski()
{
    difference()
    {
        linear_extrude(29)
        minkowski(convexity = 2)
        {
            offset(-4) base();
            circle(4);
        }

        translate([3.3, 2.75, 1])
        linear_extrude(35)
        //minkowski(convexity = 2)
        {
            //offset(-4) 
            square([68, 96]);
            //circle(4);
        }

        translate([3.3+68+3.4, 2.75, 1])
        linear_extrude(35)
        //minkowski(convexity = 2)
        {
            //offset(-4) 
            square([68, 96]);
            //circle(4);
        }

//        translate([146/2, 101.5/2, -1]) cylinder(35,r=48.5/2);
    }
  
    translate([1,1,0]) cylinder(1, 1, 0);
}