+// 3/16 inch in mm deck_depth = 4.7625;
+// 1/4 inch in mm = 6.35
+// subtract a little to be a squeeze fit
+deck_depth = 4.7625 - 0.4;
+// sonar sensor measurements taken with calipers:
+// 10.82 in between, 42.33 outside, 15.82 diameter
+// measured diameter of 15.82 with calipers,
+// but when printed ends up being too small, so add some
+sonar_diameter = 15.82 + 0.4;
+sonar_radius = sonar_diameter / 2;
+sonar_height = 13.8;
+between_sonar_centers = sonar_diameter + 10.82;
+// the sonar cylinders are placed on the pcb at slightly different positions
+// from one sensor to the next, so this allows for that variance.
+between_sonar_centers_variance = 2;
+// keep at least this much plastic surrounding the sonar cylinder on all sides
+buffer = 3;
+sonar_holder_length = buffer + between_sonar_centers + sonar_diameter + buffer;
+sonar_holder_width = buffer + sonar_diameter + buffer;
+// sonar_holder_depth is deck_depth minus a little bit to make arm fit
+// into deck holder
+sonar_holder_depth = deck_depth - 0.7875;
+
+deck_holder_length = sonar_holder_depth * 2 + deck_depth + 15;