include <BOSL2/std.scad>

top_height = 13;
top_w = 1;
bottom_height = 25;
width = 7;

t = 2;

$fn=36;
diff("R") {
    left(width/2)  cuboid([t,bottom_height,t], anchor=BACK);
    right(width/2) cuboid([t,bottom_height,t], anchor=BACK);
    cyl(h=t, d=width+t);
    tag("R") cyl(h=t, d=width-t);
    tag("R") cuboid([width-t, width-t, t], anchor=BACK);
    cuboid([t,top_height,t], anchor=FWD);
}