diff --git a/core-docs/good-enough-4u0-ship-light-spec.md b/core-docs/good-enough-4u0-ship-light-spec.md
new file mode 100644
index 0000000..91983e9
--- /dev/null
+++ b/core-docs/good-enough-4u0-ship-light-spec.md
@@ -0,0 +1,20 @@
+# Good Enough 4u0 — Ship-Light Spec
+
+**File:** `good-enough-4u0-ship-light-spec.md`
+
+## Purpose
+Minimize shipping weight/cost by only producing & shipping **custom parts**. Everything else is sourced locally as COTS.
+
+## Rules
+1. **Split BOM:**
+   - *Ship:* Only non-standard parts (3D printed, CNC routed, laser cut, etc.).
+   - *Source Local:* All Anchor COTS and fasteners.
+2. **Tool Floor:** Define the **minimum tool set** (e.g., hacksaw, drill, screwdriver). No specialty tooling unless unavoidable.
+3. **Cut List:** If local COTS require cutting, include simple measurements.
+4. **Fastener Discipline:** Stick to **common screw/bolt sizes** (M3/M5/M6 or 1/4″/5/16″/3/8″). No obscure threads.
+5. **Flat-Pack Ideal:** Designs should aim to ship flat for minimal volume.
+
+## Documentation Requirements
+- BOM table with two columns: *Ship* vs *Source Local*.
+- Tool Floor checklist.
+- Cut List with loose tolerances (e.g., “±5 mm is fine”).
diff --git a/core-docs/good-enough-4u0-supply-side.md b/core-docs/good-enough-4u0-supply-side.md
new file mode 100644
index 0000000..8f7c920
--- /dev/null
+++ b/core-docs/good-enough-4u0-supply-side.md
@@ -0,0 +1,28 @@
+# Good Enough 4u0 — Supply-Side Commons
+
+**File:** `good-enough-4u0-supply-side.md`
+
+## Purpose
+Harness leftover and salvaged materials as raw input—without making them a fragile dependency.
+
+## Two Supply Categories
+
+### 1. Opportunistic Salvage (One-Time)
+- Shop leftovers: lumber, metal offcuts, plastics.
+- Construction salvage: glass, tiles, fixtures.
+- Industrial junk streams.
+- **Rule:** Cannot be the essential anchor. Always list a repeatable substitute.
+
+### 2. Perennial Secondary Markets
+- Garage sales, flea markets, thrift stores, liquidation.
+- Common discards: shelving, office chairs, plastic tubs.
+- **Rule:** Acceptable as semi-stable source if turnover is predictable.
+
+## Documentation Requirements
+- **Material class, not brand.** (“Aluminum offcut, ≥5 mm” not “6061 from X shop.”)
+- **Substitution note.** Identify what standard material could replace it.
+- **Hazard check.** Call out risks (treated lumber, tempered glass, lead solder).
+
+## Integration with Design
+- Salvage = **enhancement, not anchor.** Anchors must remain plentiful COTS.
+- Builders must be able to finish the design without the exact salvage find.