Sometimes you have to get creative...

I am hugely curious as to how spherical the finished loaf will be.

I should probably comment, now, on what I think of this.

It's actually a viable way to proof a loaf if you really have to, but as the above photo clearly shows, it is very easy to accidentally misjudge whether the loaf is fully proved. It could have used another half an hour or so I think. Heh.