Worlds / World 3 / Product Design (2)

Kids' Heater Lunch Box

Warm belly, happy kid.

A lunch box that gently warms a kid's home-cooked meal at school. Parents control it from an app, and the lid only opens when the light turns green.

Size20 × 14.3 × 6.45 cm

WarmingBelow 60 °C

ChargingUSB-C

ControlParent app

Role: Solo · research, design, CAD, renders
Course: Product Design (2)
2025/2026
Tools: Research · SolidWorks · Rendering · App concept
Supervised by: Dr. Wesam Oney
TA Ahmed Gamil
TA Ghada El-Metwaly

01Problem

Cold lunch, no microwave

Kids take healthy food from home to school, but by lunchtime it is cold and there is no microwave to use. I wanted them to enjoy that food warm, safely, without an adult.

02Research

How food warmers work

I studied existing electric lunch boxes and how they heat food with PTC heating elements. I looked at materials (food-grade PP, stainless steel, silicone seals), power options, and what users like and dislike. Burns, price and battery life came up again and again.

Research slide on electric lunch boxes and PTC heating elements — Market and technology research.

Research slide on materials and power supply options — Materials and power.

03Requirements

Safe first

I wrote requirements in five groups: safety, durability, ease of use, portability and power. Overheat protection below 60 °C, a one-touch button a child can use, a size that fits a school backpack, rounded edges, and USB-C charging.

List of requirements in five groups — List of requirements.

04Sketch

Two concepts, then one box

I started with two concepts: a round food jar for soup or milk with cereal, with a heating pad, battery and spoon, and a clip-locked box with a split steel tray. The box won. I then sketched its layout at 20 × 15 cm, the red and green LED lock, a timer display, and where the battery, heater plate and Arduino sit inside.

Pencil sketch of a round food jar concept with handle, heating pad, battery and spoon — Concept 2: a food jar for liquids.

Pencil sketch of a box concept with clip locks, steel tray and battery — Concept 1: a clip-locked box. This one won.

Pen sketches of the chosen box: layout, LED lock, power button and timer — Layout, LED lock and timer ideas.

Pen sketch of the internals: battery, heater plate, Arduino and Wi-Fi module — Where the electronics go.

05Design

Warm on one side, fresh on the other

Part of the box heats and part does not, so fruit and snacks can share it with the warm meal. Clear windows in the lid show the snacks. Inside there is a stainless steel tray over a flat heating plate, a rechargeable battery and an Arduino with Wi-Fi. The LED ring stays red while the box is locked and turns green when it is safe to open.

Exploded render: lid, steel tray, heating plate and red base — Lid, steel tray, heating layer, base.

Technical drawing of the lunch box with dimensions — Technical drawing. Dimensions in cm.

06Born

Box and app

Parents can see the temperature, set a target, start warming, set a timer and lock the lid from an app I called Lunchbox Connect.

Renders of the lunch box closed and exploded — Final renders.

How-to-use scenes and the Lunchbox Connect app — How it is used.