// 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;