Firing Crystal-glazed Tiles

How to stack them? Flat seems to give poor crystal growth [as on my last batch of mezuzot],vertical would lead to massive glaze run,so I tried an experimental firing with various angles,as you can see. There's an interesting parallel with the positioning of the mezuza cover on one's doorpost- one opinion of our sages says horizontal,another says vertical- so we fix it at 45 degrees,as a compromise-an ancient,important and occasionally overlooked Jewish concept.