From 43810eaba0ab8e4cafc1f3811c3be28708f63c14 Mon Sep 17 00:00:00 2001
From: Eli Mallon <eli@iame.li>
Date: Tue, 12 May 2026 17:13:51 -0700
Subject: [PATCH] v4: round the cube's vertical edges (corner_r=4)

Replace the rectangular cube/wall constructions for the bottom and top
shells with `linear_extrude` of a rounded 2D footprint. Outer envelope
and interior cavity share the same radius so wall thickness stays
uniform (~2 mm) including at the corner diagonals.

Seam ledge, lip, and channel ribs are clipped to the rounded outer
envelope so they don't protrude past the rounded vertical faces.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
---
 cube.scad | 82 +++++++++++++++++++++++++++++++++++--------------------
 1 file changed, 53 insertions(+), 29 deletions(-)

diff --git a/cube.scad b/cube.scad
index 29fc82c..a36698d 100644
--- a/cube.scad
+++ b/cube.scad
@@ -27,6 +27,10 @@ wall = 2.0;
 lid_h   = 22.5;
 split_z = H - lid_h;          // bottom shell height (= 92.5)
 
+// Corner-rounding radius for the cube's four vertical edges. Outer envelope
+// and interior cavity both get the same radius so wall thickness stays uniform.
+corner_r = 4.0;
+
 // ---- snap lip (3-sided: left, right, back; no front) ----
 lip_h       = 6.0;
 lip_thick   = 1.6;
@@ -123,6 +127,18 @@ module hollow_box(z0, z1, t = wall) {
     }
 }
 
+// 2D rounded rectangle, W × D footprint, vertical edges rounded with `corner_r`
+module rounded_outer_2d() {
+    offset(r = corner_r) offset(r = -corner_r) square([W, D]);
+}
+
+// 2D footprint of the interior cavity — same rounding so wall thickness stays
+// `wall` everywhere (including the diagonal at each corner).
+module rounded_inner_2d() {
+    offset(r = corner_r) offset(r = -corner_r)
+        translate([wall, wall]) square([W - 2*wall, D - 2*wall]);
+}
+
 // 3-sided seam ledge — full 4-sided ring with the front strip cut out
 module seam_ledge_3sided() {
     difference() {
@@ -196,41 +212,49 @@ module back_port_cuts() {
 // ============================================================
 
 module bottom_shell() {
-    difference() {
-        union() {
-            // 4 outer walls — left/right/back full height, front partial (frame under panel)
-            translate([0, 0, wall])           cube([wall, D, split_z - wall]);
-            translate([W - wall, 0, wall])    cube([wall, D, split_z - wall]);
-            translate([wall, D - wall, wall]) cube([W - 2*wall, wall, split_z - wall]);
-            // front frame wall — only up to panel bottom
-            translate([wall, 0, wall])
-                cube([W - 2*wall, wall, front_frame_h - wall]);
-
-            // floor
-            cube([W, D, wall]);
-
-            // 3-sided seam ledge + lip
-            seam_ledge_3sided();
-            lip_ring_3sided();
-
-            // front channel ribs (grooves for the front panel)
-            left_front_rib();
-            right_front_rib();
-
-            // snap bumps on the lip (3 of them)
-            for (p = bump_positions)
-                translate(p) sphere(d = snap_d);
+    union() {
+        // Solid outer envelope (z=[0, split_z]) with rounded vertical edges,
+        // minus the interior cavity, the front opening above the frame wall,
+        // and the back-wall power-port cutout.
+        difference() {
+            linear_extrude(split_z) rounded_outer_2d();
+            // Hollow interior (above floor)
+            translate([0, 0, wall])
+                linear_extrude(split_z - wall + 0.01) rounded_inner_2d();
+            // Front opening — only above the frame wall (z >= front_frame_h)
+            translate([wall, -0.5, front_frame_h])
+                cube([W - 2*wall, wall + 1, split_z - front_frame_h + 0.01]);
+            back_port_cuts();
+        }
+
+        // Interior features (seam ledge / lip / ribs) — clipped to the rounded
+        // envelope so they don't square off the corners where they would otherwise
+        // protrude past the outer face.
+        intersection() {
+            union() {
+                seam_ledge_3sided();
+                lip_ring_3sided();
+                left_front_rib();
+                right_front_rib();
+            }
+            linear_extrude(split_z + lip_h + 1) rounded_outer_2d();
         }
-        back_port_cuts();
+
+        // Snap bumps (positioned safely inside the envelope, no clip needed)
+        for (p = bump_positions)
+            translate(p) sphere(d = snap_d);
     }
 }
 
 module top_shell() {
     difference() {
-        union() {
-            hollow_box(split_z, H);
-            translate([0, 0, H - wall]) cube([W, D, wall]);  // ceiling
-        }
+        // Rounded outer envelope from z=split_z to z=H
+        translate([0, 0, split_z])
+            linear_extrude(H - split_z) rounded_outer_2d();
+        // Hollow interior, stopping `wall` below H to leave a ceiling
+        translate([0, 0, split_z])
+            linear_extrude(H - split_z - wall + 0.01) rounded_inner_2d();
+        // Snap dimples (recessed into the inner wall surface)
         for (p = dimple_positions)
             translate(p) sphere(d = dimple_d);
     }
-- 
2.51.2