remove the box frame pieces, all pieces are of the extended lineage

Signed-off-by: Brian S. Stephan <bss@incorporeal.org>

src/frames/pieces/front-or-back.scad

@@ -0,0 +1,27 @@
+/*
+ * SPDX-FileCopyrightText: © 2024 Brian S. Stephan <bss@incorporeal.org>
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+include <parameters.scad>
+include <components.scad>
+use <frames/complete/left-frame.scad>
+use <side.scad>
+
+module front_or_back_frame_piece() {
+	piece_width = panel_support_width+frame_wall+frame_mount_column_width;
+	intersection() {
+		left_frame();
+		difference() {
+			// include the whole bottom wall (including mount columns)
+			translate([0, -(frame_y/2)+(piece_width/2), 0]) cube([frame_x, piece_width, frame_z], center=true);
+			// ...minus the frame wall and lip on the left
+			translate([-frame_x/2+frame_wall/2, 0, 0])
+				cube([frame_wall, frame_y, frame_z], center=true);
+			// ...minus a slot for the combining piece to go into
+			cube([frame_x, frame_y-(panel_support_width+frame_wall)*2, inner_frame_z/3], center=true);
+		}
+	}
+}
+
+front_or_back_frame_piece();