This is a clever use of space right here. These bookends keep your paperbacks in line and your mail in order. All your favourite paper goods, all in one place, tidy and organised.
I just moved apartments this weekend and am therefore acutely aware of just how much stuff—bound, enveloped, and otherwise—I have saved over the years, and I love how easily these would add a bit of order to the chaos. They're made out of Polystone, which is generally used for kitchen counters and the like, which means they'd definitely be able to survive domestic wear-and-tear.
I actually think they would be simple as hell to make if you were so inclined, using any kind of material and little boxy vessel on either end. Because at $45 (£27 excl. shipping) each, you're paying for convenience—but also clean lines and the ease of ordering online without faffing around with sourcing your own materials. [Mollaspace]