coin_dia=18.75;

difference()
{
	cylinder(r=40, h=1, $fn=30);
	difference()
	{
		cube(size=[80,80,5], center=true);
		cube(size=[40,40,5]);
	}

	translate(v=[3,10,-2]) cube(size=[2,coin_dia,5]);
	translate(v=[10,3,-2]) cube(size=[coin_dia,2,5]);
	translate(v=[18,18,-2]) cylinder(r=coin_dia/2, h=5, $fn=30);
}