diff --git a/model/common.scad b/model/common.scad
index 0a9b063..3f87d66 100644
--- a/model/common.scad
+++ b/model/common.scad
@@ -1,45 +1,88 @@
+include <BOSL2/std.scad>
+
 BASE_MODEL_SCALE = [1.1, 1, 1.1];
 BASE_MODEL_TRANSLATE = [-0.4, 0, 16.978];
+EPS = 0.01;
+$fn = 50;
 
-module main_display(){
-    // Outer dimensions, height currently unknown
-    cube([55.04, 89.3, 10]);
+module main_display() {
+  // Outer dimensions, height currently unknown
+  cube([55.04, 89.3, 10]);
 }
 
-module pad(){
-    // A button has 4.2 x 6 mm -> At least ~20x20 are required for the PCB
-    cube([20, 20, 10]);
+module pad() {
+  // A button has 4.2 x 6 mm -> At least ~20x20 are required for the PCB
+  cube([20, 20, 10]);
 }
 
-module small_display_below_main()
-{
-    // https://de.aliexpress.com/item/1005003753680706.html
-    cube([45.8, 20, 11.3]);
-    // old i2c variant:
-    //cube([43.5, 19.44, 4.5]);
+module small_display_below_main() {
+  // https://de.aliexpress.com/item/1005003753680706.html
+  cube([45.8, 20, 11.3]);
+  // old i2c variant:
+  //cube([43.5, 19.44, 4.5]);
 
-    // initial dimension ideas
-    // cube([38,16,4]);
-    // translate([150,0,0]) cube([22,5.5,4]);
+  // initial dimension ideas
+  // cube([38,16,4]);
+  // translate([150,0,0]) cube([22,5.5,4]);
 }
 
-module tertiary_display()
-{
-    // https://de.aliexpress.com/item/1005006034531826.html
-    cube([80, 36, 10]);
+module tertiary_display() {
+  // https://de.aliexpress.com/item/1005006034531826.html
+  cube([80, 36, 10]);
 }
 
-module battery() {
-    // 18650
-    rotate([0,90,0]) cylinder(d=18, h=65);
+module battery(anchor = BOTTOM) {
+  // 18650
+  rotate([0, 90, 0]) cylinder(d=18, h=65, anchor=anchor);
 }
 
-module microcontroller() {
-    // width 32 including USB-C port
-    length = 91.5;
-    height = 20;
-    battery_length = 65;
-    delta = length - battery_length;
-    cube([length, 32, height]);
-    translate([delta / 2,16, 15]) battery();
+/// USB-C port and switch not 100% dimensionally accurate, take care!
+module micro_controller(battery_holder = false, battery = false) {
+  pcb_length = 91.5;
+  pcb_height = 6.5; // including components, highest point: jst connector, followed by uC
+  pcb_height_no_components = 1.1;
+  pcb_width = 28.8;
+
+  hole_diameter = 2.5;
+  hole_inset = 1;
+  usb_protrusion = 1.7;
+  usb_width = 9;
+  usb_inset_from_pcb_end = 5;
+  power_switch_protrusion = 2.1;
+  power_switch_inset_from_pcb_end = 8.1;
+  power_switch_width = 4;
+
+  battery_holder_height = 15;
+  battery_holder_width = 21;
+  battery_holder_length = 77.3;
+
+  battery_length = 65;
+  battery_protrusion = 4.5;
+
+  difference() {
+    cuboid([pcb_length, pcb_width, pcb_height], rounding=2, edges="Z") {
+      if (battery_holder)
+        position(TOP)
+          cube([battery_holder_length, battery_holder_width, battery_holder_height], anchor=BOTTOM + CENTER) {
+            if (battery)
+              position(TOP)
+                up(battery_protrusion)
+                  battery(anchor=CENTER + LEFT);
+          }
+      position(RIGHT + BOTTOM) {
+        position(FRONT)
+          left(usb_inset_from_pcb_end)
+            cube([usb_width, usb_protrusion, pcb_height - pcb_height_no_components], orient=FRONT, anchor=RIGHT + BOTTOM + FRONT);
+        position(BACK)
+          left(power_switch_inset_from_pcb_end)
+            cube([power_switch_width, power_switch_protrusion, pcb_height - pcb_height_no_components], orient=FRONT, anchor=RIGHT + TOP + FRONT);
+      }
+    }
+
+    xcopies(pcb_length - (2 * hole_inset) - hole_diameter) {
+      ycopies(pcb_width - (2 * hole_inset) - hole_diameter) {
+        cyl(d=hole_diameter, h=pcb_height + EPS, orient=UP);
+      }
+    }
+  }
 }