Quarter of hoop for kitty

hoop.scad

/*[ Radius of big circle ]*/
r0 = 150;

/*[ Radius of tube ]*/
r1 = 8; // r0/10.0;

/*[ Tolerance ]*/
rtol = 0.2;

module joint(r) {
    linear_extrude(height=r)
    translate([r0, 0, 0])
    square(size=r, center=true);
}

union() {
    difference() {
        rotate_extrude(angle=90, $fn=180)
        translate([r0, 0, 0]) 
            circle(r=r1, $fn=360);

        rotate([-90, 0, 0])
            joint(r1+rtol);
    }

    rotate([-90, 0, 90])
        joint(r1-rtol);
}

hoop.stl