[CobaltBlue]

I was just thinking that certain crystals have similar structures, so the structure itself doesn't tell you whether the thing was constructed with intelligent design.

Unless they are arguing that repeating regular structures are evidence of intelligent design, and, I suppose, things that are amorphous evidence of no design?

[general_re]

...so the structure itself doesn't tell you whether the thing was constructed with intelligent design.

Ah, but that is exactly what ID theory says - that you can infer design purely from the structure of a thing, without any other knowledge other than of the inherent properties of the thing itself.

But I take it you're likely to be rather skeptical of that claim ;)