more designs

pump_rubbers/extra_ring.scad

@@ -0,0 +1,11 @@
+third_dia = 63;
+outer_dia = 81;
+
+$fn=50;
+
+linear_extrude(height=2, center=true, convexity=10, twist=0) {
+    difference(){
+        circle(r=outer_dia/2);
+        circle(r=third_dia/2);
+    }
+}