There is no Camp! - Stick together

Toilet key hacking

The toilet keys on the camping site consist of a plastic carrier holding a 4×3 matrix of magnets. Each magnet encodes one bit, but the pattern looks like an L-shape.

  0 = S
  1 = N
  
  1 0 0
  1 0 0
  1 0 0
  1 1 1

Someone did a draft for a 3d printed version in openscad; the magnet size is 5mm in diameter and 2mm in height.

NOTE: This is only a draft and may still need some adaption, as we didn't have enough magnets to test

  y_magnet_pos = [31,40,49,58];
  x_magnet_pos = [5,14,23];
  magnet_spacing = 9;
  magnet_dia = 5;
  magnet_h = 2;
  
  module magnet()
  {
      color([.6,.6,.6]) cylinder(d=5, h=2, $fn=30, center=true);
  }
  module camping_toilet_key()
  {
      difference() {
          cube([28,64,4]);
          translate([23,5,-.1]) cylinder(d=5, h=4.2, $fn=30);
          for(y = y_magnet_pos) {
              for(x = x_magnet_pos) {
                  translate([x, y, .8])
                  cylinder(d=magnet_dia+.4, h=magnet_h+.4, $fn=60);
                  for(xd = [-2,0,2])
                  translate([x + xd, y, 4.2]) cube([1,magnet_dia + 1,2], center=true);
              }
              translate([28/2 + 5, y, 2])
                  cube([28,magnet_dia + .1,magnet_h+.4], center = true);
              translate([28/2 - 5, y, 2])
                  cube([28, magnet_dia/2, magnet_h+.4], center = true);
              translate([28/2, y - magnet_spacing/2, 2])
                  cube([26, (magnet_spacing - magnet_dia - 1), magnet_h+.4], center = true);
          }
      }
  }
  camping_toilet_key();