// -*- C -*-

hoopthick = 3;

hinnerrad = 15;
houterrad = hinnerrad + hoopthick;
hcentredist = 10;

blockdepth = 5;
blockwidth = hcentredist*2 + 6;

module Oval(centredist, rad) {
  hull() {
    translate([-centredist/2,0,0]) circle(r=rad);
    translate([+centredist/2,0,0]) circle(r=rad);
  }
}  

module Hoop(){
  difference(){
    Oval(hcentredist, houterrad);
    Oval(hcentredist, hinnerrad);
  }
}

module Positive(){
  Hoop();
  translate([0, (blockdepth + hoopthick)/2 + hinnerrad])
    square([blockwidth,
	    blockdepth + hoopthick],
	   center=true);
}

Positive();