SL-8 ("Lumina-8") Octagonal Story Lantern

Heirloom Dual-Mode Bedside Nightlight & Point-Source Ceiling Projector
Precision multi-material architecture combining Ponoko 6.4 mm Solid American Black Walnut, OSH Cut 0.9 mm 430 Magnetic Stainless Steel Projection Cartridges, SendCutSend 3.2 mm Anodized Aluminum & 1.5 mm Black Delrin, and a DIY Clear Cast Acrylic Dry-Erase Projection Disc.

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1. Overview & Key Engineering Innovations

Most laser-cut bedside lamps fail at projection because extended light sources (LED strips, rings, or frosted bulbs) cast overlapping penumbral shadows, and thick 3.2\text{ mm} wooden stencils vignette off-axis rays above 35^\circ. The SL-8 ("Lumina-8") solves both optical and mechanical challenges in a zero-glue, fastener-clamped heirloom design built for a 4.5-year-old's bedroom:

• True Point-Source Pinhole Optics (1.45\text{ mm} Unlensed Emitter + 0.9\text{ mm} Metal Cartridges): A single bare 3\text{ W} 2700\text{ K} warm-white LED die paired with razor-thin 0.9\text{ mm} sheet-metal projection discs casts crisp, wide-angle (135^\circ) starfields and animal silhouettes across the entire ceiling and upper walls.
• Child-Safe Ferromagnetic Cartridge Ecosystem (Zero Magnets on Discs): All 4× \varnothing 6 \times 3\text{ mm} N52 neodymium magnets are permanently trapped inside the Walnut Crown Ring beneath a 1.5\text{ mm} Delrin bearing ring. The removable 430 Ferritic Stainless Steel projection discs snap magnetically onto the crown with zero glued magnets on the swappable parts.
• 4 Modular Top Cartridge Modes Included:
  1. Enchanted Boreal Forest (sl8_disc_forest.dxf): Royal antlered stag, flying barn owl, sitting woodland fox, giant evergreen pines, crescent moon, and the Big Dipper + Polaris.
  2. African Savanna Safari (sl8_disc_african_safari.dxf): Matriarch elephant with raised trunk, towering giraffe, maned lion on kopje rock, umbrella acacia tree, flocking savanna birds, and the Southern Cross (Crux).
  3. DIY Clear Cast Acrylic Dry-Erase Canvas + Magnetic Star-Frame Ring (sl8_clear_dry_erase_disc.dxf + sl8_disc_dry_erase_frame.dxf): A 3.0\text{ mm} optically clear cast acrylic disc clamped magnetically by a 16-star 430 SS aperture ring—allowing a child to draw her own shadow puppets or stained-glass ceiling projections with dry-erase and window markers.
  4. Frosted Acrylic Ceiling Ambient Glow Disc (sl8_frosted_glow_disc.dxf): A 3.0\text{ mm} Matte Frosted Cast Acrylic disc that diffuses the top pinhole beam into a wide, shadow-free warm moonlight ceiling glow, or stacks underneath metal discs to soften crisp stencils into a dreamy twilight haze.
• Solid Brass Rod Capacitive Touch Dimmer (Zero Knobs to Break or Bind): One of the 4 vertical M3 brass structural tie-rods doubles as a touch sensor electrode (electrically isolated from the aluminum base via an M3 nylon shoulder bushing). A short tap fades the lantern ON/OFF with soothing bedtime transitions; holding a finger against the brass rod smoothly ramps brightness (10% to 100%) with memory.
• Flush Rear USB-C Female Receptacle: A dedicated laser-cut pocket in the Lower Walnut Ring houses a standard USB-C female jack, allowing any standard phone or tablet charger cable to plug directly into the back of the lantern.
• 360° Kid-Safe Delrin Turntable Ring: A 16-wave scalloped 1.5\text{ mm} Black Delrin (Acetal) slip-ring lets a 4.5-year-old smoothly spin the top projection scene by hand with zero wood-on-wood scraping.
• Dual-Mode Glow \leftrightarrow Project Diffuser System: 8× slide-in 3.0\text{ mm} Matte Frosted Cast Acrylic panels convert the lantern between a soft, warm bedside reading lamp and a high-contrast ceiling projector.

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2. Engineering Specifications

Specification	Parameter	Note / Reference
Envelope Dimensions	\varnothing 140.0\text{ mm} Octagon \times 158.0\text{ mm} Tall	129.3\text{ mm} flat-to-flat; weighted low-CG base prevents tipping
Wood Architecture	6.4 mm (1/4") Solid American Black Walnut	Lower Base Ring + Upper Crown Ring + 8 sculpted radial staves (Ponoko)
Projection Cartridges	\varnothing 116.0 \times 0.9\text{ mm} 430 Magnetic Stainless	Self-supporting stencil geometry; all features \ge 1.4\text{ mm}, zero floating islands
DIY Drawing Cartridge	\varnothing 116.0 \times 3.0\text{ mm} Clear Cast Acrylic (PMMA)	Clamped magnetically beneath the 430 SS 16-Star Aperture Frame Ring
Ceiling Ambient Glow Disc	\varnothing 116.0 \times 3.0\text{ mm} Matte Frosted Acrylic	Standalone ceiling ambient moonlight wash or sub-diffuser under stencils
Heatsink Baseplate	3.2 mm (1/8") 5052 Aluminum (Black Anodized)	Passive convective venting; keeps LED base \le 30^\circ\text{C} at 3\text{ W} continuous
Power & Control	Flush 5V USB-C + Brass Rod Capacitive Touch Dimmer	Flush female Type-C port in Walnut base; tap brass rod ON/OFF, hold to dim
Optical Emitter	3W 2700K CRI 90+ Unlensed 3535 LED (20mm Star)	1.45\text{ mm} single die Cree XP-E2 (V_f \approx 3.0\text{ V})
Production BOM Cost	~$36.80 / kit (at 25-unit batch)	Target retail $149.00 (~75% gross margin); 3-disc expansion packs $4.50 BOM / $29 retail

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3. Master 5-Sheet Laser-Cut Blueprint

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3B. Power Source, Wiring Schematic & Cord Strain-Relief Architecture

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4. Documentation & Interactive Viewers

Guide / Tool	File	Description
🖥️ Interactive 3D WebGL CAD & Projection Viewer	viewer/sl8_3d_preview.html	Live Three.js 3D model with explode slider, cartridge switcher (Forest / Safari / Dry-Erase), diffuser toggle, and simulated rotating ceiling projection
🗺️ Master Cut-Sheet Blueprint	viewer/sl8_cut_sheets_blueprint.svg	1:1 mm visual layout of all Ponoko, OSH Cut, and SendCutSend sheets
🖨️ Printable Assembly Manual & QA Log	viewer/sl8_assembly_guide_printable.html	2-page print-ready shop traveler and batch QA checklist
🔌 Power & Wiring Schematic	docs/images/sl8_wiring_and_power.svg	3-panel top-down baseplate electronics layout, 5V USB-C PWM dimmer + 700mA CC driver schematic & Delrin cord strain-relief cutaway
📋 Bill of Materials & Vendor Ordering	docs/BOM_AND_MANUFACTURING.md	Complete sourcing table, Ponoko/OSH Cut/SendCutSend parameters, fastener BOM & unit economics
🛠️ Assembly & Wiring Checklist (Markdown)	docs/ASSEMBLY_GUIDE_AND_CHECKLIST.md	15-minute zero-glue assembly & soldering instructions and QA acceptance table
📐 Optical & Thermal Engineering Spec	docs/OPTICAL_AND_THERMAL_SPEC.md	Penumbra derivation, off-axis ray clipping math, dry-erase optics & thermal modeling

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5. Repository Structure & Regeneration

.
├── README.md                                      # Project overview, specs & blueprint index
├── cad/                                           # Parametric Python CAD & viewer generators
│   ├── generate_cut_files.py                      # Generates all AC1015 DXFs, SVGs & blueprint
│   ├── generate_3d_preview.py                     # Generates self-contained Three.js 3D viewer
│   └── generate_assembly_guide.py                 # Generates printable HTML/MD assembly manuals
├── cut_files/                                     # Production 1:1 mm laser-cutting files
│   ├── metal/                                     # OSH Cut / SendCutSend sheet metal
│   │   ├── sl8_alu_baseplate.dxf / .svg           # 3.2mm 5052 Aluminum heatsink baseplate
│   │   ├── sl8_disc_forest.dxf / .svg             # 0.9mm 430 SS Enchanted Boreal Forest disc
│   │   ├── sl8_disc_african_safari.dxf / .svg     # 0.9mm 430 SS African Savanna Safari disc
│   │   ├── sl8_disc_dry_erase_frame.dxf / .svg    # 0.9mm 430 SS 16-Star Dry-Erase clamping ring
│   │   ├── sl8_disc_pair_sprue.dxf / .svg         # 2-disc nested metal sheet (Forest + Safari)
│   │   └── sl8_disc_trio_sprue.dxf / .svg         # 3-disc nested metal sheet (All 3 metal discs)
│   ├── wood/                                      # Ponoko / SendCutSend hardwood
│   │   └── sl8_walnut_sheet_ponoko.dxf / .svg     # 6.4mm Walnut Base Ring, Crown Ring & 8 Staves
│   ├── delrin/                                    # SendCutSend engineering acetal
│   │   └── sl8_delrin_bearing_ring.dxf / .svg     # 1.5mm Black Delrin 360° rotary slip-ring
│   └── acrylic/                                   # Ponoko / SendCutSend cast acrylics
│       ├── sl8_frosted_diffusers.dxf / .svg       # 3.0mm Matte Frosted Acrylic 8× diffuser panels
│       ├── sl8_frosted_glow_disc.dxf / .svg       # 3.0mm Matte Frosted Acrylic ceiling glow disc
│       └── sl8_clear_dry_erase_disc.dxf / .svg    # 3.0mm Optically Clear Acrylic DIY dry-erase disc
│   ├── images/sl8_hero_render.svg                 # Isometric architectural & optical hero diagram
│   ├── BOM_AND_MANUFACTURING.md                   # Sourcing, vendor cheat sheet & unit economics
│   ├── ASSEMBLY_GUIDE_AND_CHECKLIST.md            # Step-by-step assembly SOP & QA log
│   └── OPTICAL_AND_THERMAL_SPEC.md                # Point-source optics & thermal derivations
└── viewer/                                        # Interactive 3D & printable HTML/SVG viewers
    ├── sl8_3d_preview.html                        # Interactive Three.js 3D CAD & ceiling projector
    ├── sl8_assembly_guide_printable.html          # Print-ready 2-page shop manual
    └── sl8_cut_sheets_blueprint.svg               # Master 5-sheet engineering blueprint

To regenerate all DXF/SVG cut files, blueprints, 3D viewer, and assembly guides from source:

python3 cad/generate_cut_files.py
python3 cad/generate_3d_preview.py
python3 cad/generate_assembly_guide.py