+ mirror([1,0,0])
+ translate([ (vol_xbot+vol_xtop)/2, 0, psz[2]/2 + vol_zoff ])
+ cube([ vol_xtop-vol_xbot, vol_depth*2, vol_zsz ], center=true);
+
+ translate([ thick[0], -10, -10 ])
+ cube([ 10, psz[1]+20, psz[2]+20 ]);
+
+ //translate([-50,-50,10]) cube([100,100,100]);