So did you glue two pieces of 3/4 inch thick MDF to get the 1 1/2 inches? I ask because I built a similar rack for my daughter when she went off to Purdue Univ.
The DIY rack is pretty common but the speaker stands are really nice looking. Haven't seen anyone else try that.
Check my system page for a look at my DIY rack. I used slate in place of wood, very heavy and passes the knuckle rap test.