Hi,
I have an idea, when cutting aluminium you need a coolant like terpentine or alcohol, my idea is like this, use a plastic chopping board put a very thin coat of silicon glue on the cutting objects back and put in on the chopping board let it hard and put a fat string of same silicone glue on the other side, the cutting side, and let it hard. place the assy' on your CNC router and pour the cutting solution on the surface this method should work perfect as the fluid will stay put.