diff --git a/katzenklappe.scad b/katzenklappe.scad
new file mode 100644
index 0000000..8750680
--- /dev/null
+++ b/katzenklappe.scad
@@ -0,0 +1,62 @@
+tunnel_w = 160;
+tunnel_h = 160;
+tunnel_t = 10; // tunnel thickness
+tunnel_s = 40; // tunnel spacing: overlap for screws
+door_t = 50; // door thickness
+plexy_t = 6; // thickness of plexy glass sheet
+gap = 1; // gap between parts moving relative to each other
+seal = 5;
+angle = 0;
+guide_h = 20;
+
+// calculations
+rad = 3*plexy_t/2;
+sheet_h = tunnel_h-2*seal-rad;
+
+// colors
+plexy = [0.4,0.6,1,0.6];
+snow = [1,1,1,0.5];
+wood = [0.8,0.3,0];
+
+module door(){
+    color(wood) difference(){
+        cube([1000,door_t,2000],true);
+        tunnel_core();
+    }
+}
+
+module tunnel_core(){
+    cube([tunnel_w+2*tunnel_t,door_t+2*tunnel_t,tunnel_h+2*tunnel_t],true); // eigentlicher tunnel
+}
+
+module tunnel(){
+    color(snow)difference(){
+        union(){
+            tunnel_core();
+            translate([0,(door_t+tunnel_t)/2,0])  cube([tunnel_w+2*tunnel_s,tunnel_t,tunnel_h+2*tunnel_s],true); // krempe
+            translate([0,(door_t+tunnel_t)/-2,0]) cube([tunnel_w+2*tunnel_s,tunnel_t,tunnel_h+2*tunnel_s],true); // krempe
+        }
+        cube([tunnel_w,door_t+2*tunnel_t+2,tunnel_h],true); // loch
+    }
+}
+
+module sheets(){
+    translate([0,-plexy_t,-sheet_h/2])cube([tunnel_w-2*seal,plexy_t,sheet_h],true);
+    translate([0, plexy_t,-sheet_h/2])cube([tunnel_w-2*seal,plexy_t,sheet_h],true);
+
+    translate([0,0,guide_h/2-sheet_h])cube([10,plexy_t,guide_h],true);
+}
+
+module flap(){
+    translate([0,0,(sheet_h-rad)/2]) rotate([angle,0,0]) union(){
+        difference(){
+            rotate([0,90,0]) cylinder(d=3*plexy_t,h=tunnel_w-2*seal,center=true);
+            sheets();
+        }
+        color(plexy)sheets();
+    }
+}
+
+*door();
+*tunnel();
+flap();