diff --git a/gridbeam.scad b/gridbeam.scad
index c21bbb0..8818611 100644
--- a/gridbeam.scad
+++ b/gridbeam.scad
@@ -8,7 +8,10 @@
 // zBeam(segments) - create a vertical gridbeam strut 'segments' long
 // xBeam(segments) - create a horizontal gridbeam strut along the X axis
 // yBeam(segments) - create a horizontal gridbeam strut along the Y axis
-// shelf(width, height) - create a shelf suitable for use in gridbeam structures width and height in 'segments'
+// topShelf(width, depth, corners) - create a shelf suitable for use in gridbeam structures width and depth in 'segments', corners == 1 notches corners
+// bottomShelf(width, depth, corners) - like topShelf, but aligns shelf to underside of beams
+// backBoard(width, height, corners) - create a backing board suitable for use in gridbeam structures width and height in 'segments', corners == 1 notches corners
+// frontBoard(width, height, corners) - like backBoard, but aligns board to front side of beams
 // translateBeam([x, y, z]) - translate gridbeam struts or shelves in X, Y, or Z axes in units 'segments'
 
 include <units.scad>
@@ -56,9 +59,11 @@ module translateBeam(v) {
 	}
 }
 
-module shelf(width, depth) {
+module topShelf(width, depth, corners) {
 	difference() {
 		cube([width * $beam_width, depth * $beam_width, $beam_shelf_thickness]);
+
+		if (corners == 1) {
 		translate([-1,  -1,  -1])
 		cube([$beam_width + 2, $beam_width + 2, $beam_shelf_thickness + 2]);
 		translate([-1, (depth - 1) * $beam_width, -1])
@@ -67,5 +72,34 @@ module shelf(width, depth) {
 		cube([$beam_width + 2, $beam_width + 2, $beam_shelf_thickness + 2]);
 		translate([(width - 1) * $beam_width, (depth - 1) * $beam_width, -1])
 		cube([$beam_width + 2, $beam_width + 2, $beam_shelf_thickness + 2]);
+		}
 	}
+}
+
+module bottomShelf(width, depth, corners) {
+	translate([0,0,-$beam_shelf_thickness])
+	topShelf(width, depth, corners);
+}
+
+module  backBoard(width, height, corners) {
+	translate([$beam_width, 0, 0])
+	difference() {
+		cube([$beam_shelf_thickness, width * $beam_width, height * $beam_width]);
+
+		if (corners == 1) {
+		translate([-1,  -1,  -1])
+		cube([$beam_shelf_thickness + 2, $beam_width + 2, $beam_width + 2]);
+		translate([-1, -1, (height - 1) * $beam_width])
+		cube([$beam_shelf_thickness + 2, $beam_width + 2, $beam_width + 2]);
+		translate([-1, (width - 1) * $beam_width, -1])
+		cube([$beam_shelf_thickness + 2, $beam_width + 2, $beam_width + 2]);
+		translate([-1, (width - 1) * $beam_width, (height - 1) * $beam_width])
+		cube([$beam_shelf_thickness + 2, $beam_width + 2, $beam_width + 2]);
+		}
+	}
+}
+
+module frontBoard(width, height, corners) {
+	translate([-$beam_width - $beam_shelf_thickness, 0, 0])
+	backBoard(width, height, corners);
 }
\ No newline at end of file