module via() {
     cylinder(h=10,r=0.5,center=true,$fn=12);
}

// TTGO T7
module esp32() {
     for(x=[0, 1, 10, 11]) {
          for(y=[0 : 9]) {
               translate([2.54*x,2.54*y,0]) via();
          }
     }
}

// https://learn.adafruit.com/stereo-3-7w-class-d-audio-amplifier/assembly
module amp() {
     for(x=[0 : 8]) {
          translate([0,2.54*x,0]) via();
     }
}

module wire_pack() {
     for(x=[0 : 4]) {
          translate([0,4*x,0]) via();
     }
}

difference() {
     union() {
          cube([40,80,1.25]);
          translate([12.5,60,0.5]) cube([15,10,3.5]);
     }

     translate([6.25,8.5,0]) esp32();
     translate([11.5,-1.5,-1]) cube([17,15,3]);

     // rows

     // row output pins wired here
     translate([5,36,0]) wire_pack();
     // 220Ω between these
     translate([15,36,0]) wire_pack();
     // these go to pins 3 of each qrd1114

     // same output pins wired here
     translate([25,36,0]) wire_pack();
     // 10k0Ω between these
     translate([35,36,0]) wire_pack();
     // these go to pins 1 of each qrd1114

     // columns: ouput pins directly to pins 2&4 of each qrd1114


     translate([30,57.5,0]) rotate([0,0,90]) amp();
}