This model pulls the compound curvature surface from the speaker into the stand for a clean look.  It has 4 bolt holes, though I'm only using the back two.  The front two require a shorter SHCS and some creativity on torquing.

I printed the version with the inside is hollowed out (shell in the models).  Otherwise, the shallow angle needs lots of extra support and wasted material.  No method included for sand filling, but if you try the layer pause, remember to turn off your fan!