The logical choice was Axiom's Full Metal Bracket...but it's no where to be found on their website.

There are angled speaker stands available, like the Kanto S6 (16º) and the Audioengine DS2 (15º). They're meant to angle speakers upwards on a desktop, but they can also angle speakers downwards if you place them on your elevated shelf. The M2 is too big to use the smaller S4 and DS1 stands.

Author of "Status 101: How To Keep Up In A World That Keeps Score While Buying Into Buying Less"