Pumpkin Sentinel — Smart Proximity-Activated Halloween Lantern

Elevator pitch
Pumpkin Sentinel is a compact 3D-printed pumpkin lamp that wakes up when people come close — soft ambient glow for cozy nights, bright alert mode when someone approaches. Built for low power and high charm, it combines mechanical craft with simple sensing intelligence to create a tactile, delightful interactive object.

Concept & Value

• What it is: A small decorative pumpkin lamp that automatically detects nearby motion and reacts with animated lighting sequences.
• Why it matters: Combines home decor with playful interactivity — perfect for Halloween displays, bedside mood lighting, or as a low-power “guest detector” at events.
• Key selling points: Modular 3D printed shell, plug-and-play electronics, safe low-voltage operation, easy to customize and print on Bambu Lab printers.

Features

• Proximity trigger: PIR motion sensor (primary) + optional ultrasonic sensor for more reliable near-field detection.
• Three lighting modes: Idle (soft warm glow), Approach (gentle fade + warm brighten), Alert (animated flicker or color loop).
• Smart timing: Adjustable timeout (e.g., 10s / 30s / 60s) after last detection.
• Power options: USB-C power bank / wall adapter or internal Li-ion (with charging circuit).
• Modular shell: Snap-fit 3D parts — replaceable faceplates for different expressions.
• Safe output: LEDs run at 5 V through driver; electronics isolated inside base.
• Bambu Lab friendly: Designed to print without supports where possible; parts oriented for P1S efficiency.

Components (BOM — minimal)

• 1 × microcontroller: ATtiny85 or ESP32-C3 (if Wi-Fi features desired)
• 1 × PIR sensor (HC-SR501 or compact module)
• (Optional) 1 × ultrasonic sensor (HC-SR04 or JSN-SR04T waterproof)
• 1 × LED ring or strip: WS2812B (8–16 LEDs) or simple warm-white LED array + MOSFET driver
• 1 × 5 V buck/boost or USB-C power module (TP4056 if using single Li-ion)
• 1 × small Li-ion cell (optional) + protection board (if battery powered)
• Passive parts: resistor, capacitor, MOSFET (IRLZ44-like), jumper, switch, micro USB/USB-C cable
• Mechanical: heat-set inserts M2/M3, 2× small magnets for snap cover, silicone gasket (optional)

Electronics & Behavior (simple firmware logic)

1. Boot: show “breathing” warm LED at 10–20% brightness (idle).
2. Sense loop: poll PIR with debounce (50–200 ms). If trigger → start Approach routine.
3. Approach routine: smooth fade from idle to 60–100% brightness in 300–700 ms; play a short animation (glow pulse or eye blink).
4. Alert routine: if continued motion or sustained proximity, switch to Alert pattern (flicker or color cycle) for max safety/visibility.
5. Timeout: after configured inactivity period, ramp down back to idle.
6. Edge cases: use hysteresis and minimum on-time to avoid rapid flicker when multiple people pass quickly.

Mechanical design notes (3D / Bambu Lab guidance)

• Overall size: keep under Ø120 × H120 mm for easy printing and portability. (Adjust to contest rules.)
• Shell: two halves — front decorative shell (pumpkin ribs + face) and rear electronics bucket. Snap-fit using magnets or clips.
• Diffuser: internal frosted dome to soften WS2812/RGB hotspots. Use 2–3 mm translucent PETG.
• Mounts: integrated standoffs for PCB, 4 × M2 heat-set inserts for secure fastening.
• Ventilation & access: small vent slots hidden in design for heat and sensor line-of-sight.
• Print settings (P1S recommended): PLA or PETG for shell; 0.20–0.28 mm layer; 3 perimeters; 15–25% infill gyroid; no supports where possible — add chamfers to avoid overhangs.
• Tolerance: snap features +0.15 mm; magnet pockets snug to avoid rattle.

Materials & Finishing

• Shell: PLA+ (easy, crisp detail) or PETG (weather resistant).
• Diffuser: Translucent PETG or thin frosted acrylic.
• Exterior finish: sand + primer + matte paint (pumpkin orange + antique wash) or filament color selection for two-tone effect.
• Grip: small rubber pad on base for stability.

Safety & Power

• Keep electronics at 5 V; if battery used, include BMS and proper charging.
• Isolate mains — use external USB adapter for wall power, do not design AC inside the unit.
• Ensure PIR sensor has unobstructed field of view and is placed >2 cm behind diffuser to avoid false trigger from internal air currents.

Assembly & Testing checklist

1. Flash microcontroller with default firmware (idle/approach/alert + config options).
2. Fit PCB into standoffs, secure with screws. Connect LED ring and sensor wiring.
3. Clip on diffuser and front shell; test for light leaks.
4. Power via USB; verify idle breathing light.
5. Walk within ~1–3 m of lamp to check detection distance and adjust PIR sensitivity and timeout.
6. Test battery charging (if used) and verify thermal profile after 30 min.

Contest submission package (recommended)

• Render images: 3× (front, side with shell removed to show internals, in-use night scene).
• 1 short demo video (15–30s) showing approach → light reaction.
• STL files: shell_front.stl, shell_back.stl, diffuser.stl, mount.stl (print-ready).
• PCB schematic + BOM (PDF).
• README (1 page): features, build steps, safety notes, and customization ideas.
• Elevator pitch (20–40 words) + longer description (100–150 words).

Demo copy (100–150 words) — use in contest description

Pumpkin Sentinel is a playful, pocket-sized Halloween lantern that senses when someone approaches and comes to life with warm, animated lighting. Designed for fast 3D printing on Bambu Lab machines, it pairs a decorative snap-fit pumpkin shell with a low-power microcontroller, an efficient PIR proximity sensor and a soft, frosted diffuser over programmable LEDs. The lamp operates from USB-C power or an internal Li-ion battery and includes adjustable timeout and sensitivity settings. It’s safe, modular and made to be customized — swap faceplates, change light patterns, or scale the model for different atmospheres. Pumpkin Sentinel turns ordinary ambient light into delightful interactivity.

Link light sensor: https://bom.so/nLgPoi