len = 54.3 - 1; bigdep = 10.7 - 1; smalldep= 4.9 - 1; tallw1 = 3.5 - 1.5; tallw2 = 3.5 - 1.5; // ish totalw = 11.6 - 2; gapw = totalw - tallw1 - tallw2; difference() { cube([len, totalw, bigdep]); translate([-1, tallw2, smalldep]) cube([len+2, gapw, bigdep - smalldep + 1]); }