update xyPlate with more support and ventilation

rack/xyPlate.scad

@@ -9,6 +9,7 @@ xyPlateConnDy = yBarDepth - 2*basePlateScrewMountToYBarXZFace; // Y distance bet
 module xyPlate() {
 
   translate(v=-[connPosX,connPosY,0]) // center around one of the YBarConnector holes
+  applyVentilation()
   applyYBarConnectors()
   plateBody();
 
@@ -23,8 +24,40 @@ module xyPlate() {
     plateBodyY = (yBarDepth - 2*xBarY) - xySlack;
     plateBodyH = xBarWallThickness;
 
-    translate(v=[xySlack/2, xySlack/2, 0])
+    translate(v=[xySlack/2, xySlack/2, 0]) {
       cube(size = [plateBodyX, plateBodyY, plateBodyH]);
+
+      // bracing
+      braceThickness = 3;
+      braceHeight = 2;
+      translate(v = [0, 0, plateBodyH])
+      difference() {
+        cube(size = [plateBodyX, plateBodyY, braceHeight]);
+        translate(v=[braceThickness, braceThickness,0])
+        cube(size=[plateBodyX-2*braceThickness, plateBodyY-2*braceThickness, braceHeight]);
+      }
+
+    }
+  }
+
+  module applyVentilation() {
+
+    apply_n() {
+      numSlits = 5;
+      edgePadding = 30;
+      diff = (xBarX-2*edgePadding)/(numSlits-1);
+      slitWidth = 4;
+      slitLength = (yBarDepth - 2*xBarY)-2*edgePadding;
+
+      for(i=[0:numSlits-1]) {
+        translate(v=[edgePadding+diff*i-slitWidth/2, edgePadding,0])
+        minkowski() {
+          cylinder(h=1,r=2);
+          cube(size=[slitWidth,slitLength,inf]);
+        }
+      }
+      children(0);
+    }
   }
 
   module applyYBarConnectors() {