I have a wavey, full length mirror in my room. I'm not an expert on the mirror crafting profession but this one in particular baffles me. How do they do that without cracking the glass? The mundane answer would be some sort of saw.

Personally, I have narrowed it down to three much more likely options:

1: Whilst the glass is still soft enough to mold, it is positioned carefully between two particularly flabby hippos. The uniformity of the wave is accounted for by special hippo/fat training in which the hippo is able to shift the interior structure of its bulk on command in return for rainbow drops (which hippos love).

2: The glass is used in the impish Olympics as sledging track. They generally last a few years before the curves become worn down too deep for the imps to safely manoeuvre a tiny sled down its banks. They then turn the glass over and use the other side for the next few years. The creates a productivity rate of 1 mirror every decade or so which I feel is justified since in my lifetime I have only seen 7, of which two have been in my possession. This makes me feel quite guilty about breaking the last one.

3: It is some sort of frozen river, stream or brook.