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+# OpenSCAD Projects
+
+Parametric 3D-printable parts designed in [OpenSCAD](https://openscad.org/). Each project lives in its own folder with a `.scad` source file, a `README.md`, and a `preview.png` render.
+
+Designs are tuned for FDM printing on a **Bambu Lab P2S** (256 × 256 × 256 mm build volume).
+
+## Requirements
+
+- [OpenSCAD](https://openscad.org/downloads.html) 2021.01 or newer (tested with the Customizer UI)
+- A slicer for your printer (e.g. Bambu Studio)
+
+Most models here use **vanilla OpenSCAD** only. Future projects may use [BOSL2](https://github.com/BelfrySCAD/BOSL2); see `.cursor/skills/openscad-bosl2/` for house-style conventions when working with that library.
+
+## Quick start
+
+1. Clone the repo and open a project's `.scad` file in OpenSCAD.
+2. Adjust parameters in the **Customizer** panel (View → Customizer).
+3. Press **F6** to render, then **File → Export → Export as STL**.
+4. Slice and print. Generated `.stl` files are gitignored; export locally as needed.
+
+## Projects
+
+| Preview | Project | Description |
+|---------|---------|-------------|
+| ![Ring Solar Siding Adapter](ring-solar-siding-adapter/preview.png) | [ring-solar-siding-adapter](ring-solar-siding-adapter/) | Adapter plate to mount a Ring Solar Charger on horizontal beaded vinyl lap siding |
+
+## Preview images
+
+OpenSCAD can export **PNG** previews from the command line when OpenGL is available (local GUI, or headless via `xvfb-run`):
+
+```bash
+openscad --render --viewall --imgsize=1200,900 \
+  -o ring-solar-siding-adapter/preview.png \
+  ring-solar-siding-adapter/ring-solar-siding-adapter.scad
+```
+
+OpenSCAD does **not** export JPG natively; convert PNG if needed.
+
+**Headless WSL / CI** — install PyVista for the script's fallback renderer (smooth shaded, no wireframe):
+
+```bash
+pip install pyvista
+python3 scripts/render-preview.py ring-solar-siding-adapter
+```
+
+**Best quality (native OpenSCAD look)** — install a virtual display so OpenSCAD can export PNG directly:
+
+```bash
+sudo apt install xvfb
+python3 scripts/render-preview.py ring-solar-siding-adapter
+```
+
+The script tries OpenSCAD + `xvfb-run` first, then falls back to PyVista.
+
+## Repository layout
+
+```
+openscad-projects/
+├── README.md
+├── AGENTS.md
+├── .gitignore                         # Ignores exported *.stl files
+├── scripts/
+│   └── render-preview.py              # Headless preview generator
+└── <project-name>/
+    ├── README.md                      # Purpose, parameters, workflow
+    ├── preview.png                    # Catalog render (committed)
+    ├── <project-name>.scad            # Parametric source
+    └── *.backup.scad                  # Optional design checkpoints
+```
+
+When adding a new project, create a kebab-case folder, add a single primary `.scad` file, write a README describing purpose and parameters, and generate a preview.
+
+## Printer
+
+Designs target a **Bambu Lab P2S**. Build volume and material notes live in [`.cursor/skills/openscad-bosl2/references/bambu-p2s.md`](.cursor/skills/openscad-bosl2/references/bambu-p2s.md). Parts from this repo should fit within 256 × 256 × 256 mm unless noted otherwise.
+
+## License
+
+No license file is included yet. Add one before publishing or sharing models externally.
diff --git a/ring-solar-siding-adapter/README.md b/ring-solar-siding-adapter/README.md
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+# Ring Solar Siding Adapter
+
+![Preview](preview.png)
+
+Parametric adapter plate that sits between a **Ring Solar Charger** (integrated battery-doorbell solar unit) and horizontal beaded vinyl lap siding.
+
+| | |
+|---|---|
+| **Source** | [`ring-solar-siding-adapter.scad`](ring-solar-siding-adapter.scad) |
+| **Footprint** | ~93 × 171 mm (matches the Ring back) |
+| **Units** | Millimeters throughout |
+
+## What it is
+
+- **Front face:** flat — the Ring unit mounts here.
+- **Rear face:** shaped to match siding — bead groove at the top, flat shelf in the middle, curved taper at the bottom.
+
+## What it's for
+
+The Ring's back is flat; siding is not. Without an adapter, you get gaps, uneven pressure, and a poor mount.
+
+This plate:
+
+- Conforms to the siding profile so the rear sits flush against the wall.
+- Receives the siding bead in a semicircular groove near the top.
+- Provides two through-holes aligned with the Ring's house-mount screws — screws pass through Ring → adapter → siding → sheathing.
+
+Typical stack:
+
+```
+Ring Solar Charger
+       ↓ screws
+  Adapter plate  ← this part
+       ↓
+  Vinyl siding
+       ↓
+  Sheathing
+```
+
+## Rear profile (side view, bottom → top)
+
+```
+plate top ─────────────  bead coping groove (receives siding bead)
+            flat rear shelf
+taper start ─────────────  flat_upper_ratio sets this boundary
+            curved taper
+plate bottom ────────────  deepest projection toward front
+```
+
+**Depth convention:** lower depth = toward the wall; higher depth = toward the front (Ring).
+
+## Parameters
+
+### Plate
+
+| Parameter | Meaning |
+|-----------|---------|
+| `plate_width` | Width of the adapter (Ring back width). |
+| `plate_height` | Height of the adapter (Ring back height). |
+| `min_wall_thickness` | Minimum solid depth at the thinnest point (bead groove pinch). Also scales bottom taper reach. |
+| `edge_round` | Rounds front edges via minkowski. Keep `0` while tuning; set ~1 for final print (slower render). |
+
+### Siding profile
+
+| Parameter | Meaning |
+|-----------|---------|
+| `siding_projection` | Nominal max siding depth from wall. Feeds `face_inset_z` via clearance and inset. |
+| `face_inset_depth` | How far the flat upper rear sits in from max projection. |
+| `bead_coping_radius` | Radius of the semicircular bead groove (measured on your siding). |
+| `bead_coping_offset_top` | Distance from plate top to center of the bead groove. |
+| `flat_upper_ratio` | Fraction of plate height (from top down) with a flat rear. Lower = taper starts higher. |
+| `bottom_taper_depth_ratio` | How far the bottom rear reaches toward the front beyond the flat shelf: `min_wall_thickness × this`. Higher = more projection at bottom. |
+| `rear_extension` | Pushes flat rear and taper toward the wall without moving the front face or bead groove vs front/top. Adds overall depth. |
+| `course_pitch` | Bead-to-bead spacing on your siding (~6.5"). Reference for tuning. |
+| `profile_segments` | Curve sampling resolution. Higher = smoother, slower. |
+| `profile_mode` | `curved` = smooth taper; `stepped` = debug fallback with sharp transitions. |
+| `rear_clearance` | Small gap so the part doesn't bind on siding. |
+
+**Common tuning relationships:**
+
+| Goal | Parameter |
+|------|-----------|
+| Move taper start up/down | `flat_upper_ratio` |
+| Bottom taper more/less toward front | `bottom_taper_depth_ratio` |
+| Whole plate deeper front-to-back (bead stays put) | `rear_extension` |
+| Bead groove up/down | `bead_coping_offset_top` |
+| Groove size | `bead_coping_radius` |
+
+### Mounting holes
+
+| Parameter | Meaning |
+|-----------|---------|
+| `mount_hole_offset_top` | Upper hole center distance from plate top. |
+| `mount_hole_offset_bottom` | Lower hole center distance from plate bottom. |
+| `mount_hole_dia` | Hole diameter (4.5 mm for 4 mm Ring screws). |
+| `mount_hole_x` | Horizontal offset from center (`0` = centered). |
+
+### Export
+
+| Parameter | Meaning |
+|-----------|---------|
+| `part_mode` | What to generate (see below). |
+| `profile_strip_width` | Width of the narrow siding fit-test strip. |
+| `front_slice_depth` | Thickness of the front-face test cap (mm). |
+
+**Export modes:**
+
+| Mode | Purpose |
+|------|---------|
+| `full` | Complete adapter with holes — final part. |
+| `profile_strip` | Narrow strip through the rear profile — cheap siding fit test. |
+| `front_slice` | Thin front cap with holes — check width, height, hole placement vs Ring. |
+
+## Suggested workflow
+
+1. **`profile_strip`** — tune siding profile (`flat_upper_ratio`, `bottom_taper_depth_ratio`, `rear_extension`, bead params).
+2. **`front_slice`** — verify Ring hole alignment.
+3. **`full`** — print final plate (PETG/ASA recommended outdoors; PLA OK for tests).
+
+**Print orientation:** front face (Ring side) on the bed, rear profile vertical.
+
+## Related files
+
+| File | Purpose |
+|------|---------|
+| [`ring-solar-siding-adapter.backup.scad`](ring-solar-siding-adapter.backup.scad) | Earlier geometry — flat upper rear + lower taper only, no bead coping groove |
+| `*.stl` | Exported meshes (gitignored; export locally) |
+
+## Regenerate preview
+
+From the repo root:
+
+```bash
+pip install pyvista                    # headless fallback (WSL without display)
+sudo apt install xvfb                  # optional — native OpenSCAD PNG export
+python3 scripts/render-preview.py ring-solar-siding-adapter
+```
+
+Or export a PNG directly from OpenSCAD when a display (or `xvfb-run`) is available:
+
+```bash
+xvfb-run -a openscad --render --viewall --imgsize=1200,900 \
+  -o ring-solar-siding-adapter/preview.png \
+  ring-solar-siding-adapter/ring-solar-siding-adapter.scad
+```
diff --git a/ring-solar-siding-adapter/preview.png b/ring-solar-siding-adapter/preview.png
new file mode 100644
index 0000000..ac45357
Binary files /dev/null and b/ring-solar-siding-adapter/preview.png differ
diff --git a/ring-solar-siding-adapter.backup.scad b/ring-solar-siding-adapter/ring-solar-siding-adapter.backup.scad
similarity index 100%
rename from ring-solar-siding-adapter.backup.scad
rename to ring-solar-siding-adapter/ring-solar-siding-adapter.backup.scad
diff --git a/ring-solar-siding-adapter.scad b/ring-solar-siding-adapter/ring-solar-siding-adapter.scad
similarity index 100%
rename from ring-solar-siding-adapter.scad
rename to ring-solar-siding-adapter/ring-solar-siding-adapter.scad
diff --git a/scripts/render-preview.py b/scripts/render-preview.py
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+#!/usr/bin/env python3
+"""Render a preview PNG for an OpenSCAD project folder.
+
+Prefers OpenSCAD's native PNG export (needs a display or xvfb-run). Falls back
+to PyVista offscreen rendering from an exported STL (no display required).
+
+Usage:
+    python3 scripts/render-preview.py ring-solar-siding-adapter
+    python3 scripts/render-preview.py ring-solar-siding-adapter --output custom.png
+
+Dependencies (fallback path only):
+    pip install pyvista
+    sudo apt install xvfb   # optional, enables native OpenSCAD PNG export
+"""
+
+from __future__ import annotations
+
+import argparse
+import shutil
+import subprocess
+import sys
+import tempfile
+from pathlib import Path
+
+REPO_ROOT = Path(__file__).resolve().parents[1]
+
+
+def find_scad(project_dir: Path) -> Path:
+    matches = sorted(project_dir.glob("*.scad"))
+    matches = [p for p in matches if not p.name.endswith(".backup.scad")]
+    if len(matches) != 1:
+        names = ", ".join(p.name for p in matches) or "(none)"
+        raise SystemExit(f"Expected exactly one .scad in {project_dir}, found: {names}")
+    return matches[0]
+
+
+def export_stl(scad: Path, stl: Path) -> None:
+    cmd = ["openscad", "--export-format=binstl", "-o", str(stl), str(scad)]
+    result = subprocess.run(cmd, capture_output=True, text=True)
+    if result.returncode != 0:
+        sys.stderr.write(result.stderr or result.stdout)
+        raise SystemExit(f"openscad STL export failed ({result.returncode})")
+
+
+def render_openscad_png(scad: Path, png: Path, width: int, height: int) -> bool:
+    """Return True if OpenSCAD wrote a PNG (requires display or xvfb-run)."""
+    openscad = ["openscad", "--render", "--viewall", f"--imgsize={width},{height}"]
+    xvfb = shutil.which("xvfb-run")
+    cmd = ([xvfb, "-a"] if xvfb else []) + openscad + ["-o", str(png), str(scad)]
+    result = subprocess.run(cmd, capture_output=True, text=True)
+    if result.returncode == 0 and png.is_file() and png.stat().st_size > 0:
+        return True
+    if result.stderr:
+        sys.stderr.write(result.stderr)
+    return False
+
+
+def render_pyvista_png(stl: Path, png: Path, width: int, height: int) -> None:
+    try:
+        import pyvista as pv
+    except ImportError as exc:
+        raise SystemExit(
+            "No display for OpenSCAD PNG export and PyVista is not installed.\n"
+            "Install one of:\n"
+            "  sudo apt install xvfb          # native OpenSCAD previews\n"
+            "  pip install pyvista            # headless fallback"
+        ) from exc
+
+    pv.OFF_SCREEN = True
+    mesh = pv.read(stl)
+    plotter = pv.Plotter(off_screen=True, window_size=(width, height))
+    plotter.set_background("#1a2332")
+    plotter.add_mesh(mesh, color="#6bb3dc", smooth_shading=True, show_edges=False)
+    plotter.camera_position = "iso"
+    png.parent.mkdir(parents=True, exist_ok=True)
+    plotter.show(screenshot=str(png), auto_close=True)
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument(
+        "project",
+        type=Path,
+        help="Project folder name or path (e.g. ring-solar-siding-adapter)",
+    )
+    parser.add_argument(
+        "--output",
+        type=Path,
+        help="Output PNG path (default: <project>/preview.png)",
+    )
+    parser.add_argument("--width", type=int, default=1200)
+    parser.add_argument("--height", type=int, default=900)
+    parser.add_argument(
+        "--force-fallback",
+        action="store_true",
+        help="Skip OpenSCAD PNG and use PyVista STL render",
+    )
+    args = parser.parse_args()
+
+    project_dir = args.project
+    if not project_dir.is_absolute():
+        project_dir = REPO_ROOT / project_dir
+    project_dir = project_dir.resolve()
+    if not project_dir.is_dir():
+        raise SystemExit(f"Project directory not found: {project_dir}")
+
+    scad = find_scad(project_dir)
+    png = args.output or (project_dir / "preview.png")
+    if not png.is_absolute():
+        png = project_dir / png
+
+    if not args.force_fallback and render_openscad_png(scad, png, args.width, args.height):
+        print(f"Wrote {png} (OpenSCAD)")
+        return
+
+    with tempfile.TemporaryDirectory() as tmp:
+        stl = Path(tmp) / "preview.stl"
+        export_stl(scad, stl)
+        render_pyvista_png(stl, png, args.width, args.height)
+
+    print(f"Wrote {png} (PyVista fallback)")
+
+
+if __name__ == "__main__":
+    main()