<?xml version='1.0' ?>
<fabmetheus>
	<path id='rings'>
		<path id='ring_outer'>
			<circle radius='10'/>
			<circle radius='8'/>
		</path>
		<path id='ring_inner'>
			<circle radius='6'/>
			<circle radius='4'/>
		</path>
	</path>
	<extrude target='=document.getElementByID(rings)'/>
	<!--
	<difference id='ring_outer'>
		<circle radius='10'/>
		<circle radius='8'/>
	</difference>
	<difference id='ring_inner'>
		<circle radius='6'/>
		<circle radius='4'/>
	</difference>
	<union>
		<extrude target='=document.getElementByID(ring_outer)'/>
		<extrude target='=document.getElementByID(ring_inner)'/>
	</union>
	-->
</fabmetheus>
