Penny Pal: A goal-based savings companion for kids

This project explores a Smart Piggy bank System that goes beyond traditional saving to teach children how to save with purpose. While conventional piggy banks and school-led saving schemes encourage putting money aside, they rarely guide children on how to save strategically toward a goal. This project seeks to bridge that gap.

Inspired by how children learn arithmetic through everyday actions like adding coins or calculating change, this concept introduces structured, goal-based saving through interaction. The piggy bank functions as a mini banking system, internally organizing deposited coins to make savings visible and purposeful.

I am currently working with two conceptual approaches. The first is a goal-based model where a child sets a specific savings target and receives weekly guidance on how much to save. The second draws from the simplified 50-30-20 principle, where only a portion of the saved amount is accessible, encouraging discipline and delayed gratification. By combining saving with intention and planning, the piggy bank becomes an active learning tool rather than a passive container.

Concept & Rationale

Children are often told to save money, but rarely taught how to save wisely. Many accumulate coins without a clear purpose, leading to impulsive spending once the money is accessed. This pattern often continues into adulthood. I observed similar contrasts among colleagues on the same payroll-some struggled before month-end, while others managed comfortably. This raised a key question: why does saving feel intuitive for some, but not for others?

This reflection led to the idea of teaching children not just to save, but to save with intention.

In India, physical coin saving is becoming increasingly rare. UPI has made transactions invisible, fast, frictionless, and abstract. But for a child learning about money for the first time, that abstraction is a problem. The weight of a coin, the sound of it dropping, the deliberate act of choosing and depositing, these physical moments make money real in a way a UPI transaction never can.

Designing for the Senses

I've noticed that the things children engage with most deeply are rarely the ones that look the most impressive, they're the ones that feel the most alive. The ones that respond, that make sounds, that change when you interact with them.

There's a reason for that. The more senses involved in an action, the more intuitive it feels, the more it holds attention, and the more it is remembered. A single tap on a screen engages almost nothing. But dropping a coin into a slot - feeling its weight, hearing it fall, pressing a button, watching a light change, hearing a voice respond - that's five distinct sensory moments from one small act.

Penny Pal is deliberately designed around this. Every coin deposit is a multisensory experience:

Touch - the weight of the coin, the press of a button
Sound - the coin dropping, the servo opening, the voice feedback
Sight - the progress lights filling up, the celebration flash at milestones
Action & Response - the flap physically opening only after the child makes a choice

This isn't decoration. Each sensory layer reinforces the intention behind the action - you chose to save, the system acknowledged it, and something in the world changed because of you.
That feeling of consequence is what makes saving feel real.

Penny Pal is built around that physicality. The interaction is intentional, not incidental.

The Penny Pal Piggy Bank introduces goal-oriented saving, where a child sets a specific target (with parental guidance) and works toward it through consistent contributions and delayed access to funds. Saving becomes a structured and intentional process rather than simple accumulation.

Through this process, the child learns:

Restraint and patience
Delayed gratification
Foundational financial awareness
An understanding of planning over impulsive spending

To reinforce positive saving behavior, the Penny Pal Bank rewards the child upon successful completion of a goal by adding a small amount of interest to the saved total, introducing simplified real-world financial principles in an age-appropriate manner. Parents act as facilitators rather than enforcers, guiding reflection and discussion instead of merely controlling access to money.

At its core, this project reimagines the traditional piggy bank as a Smart Piggy Bank, an interactive system that encourages purposeful saving and helps children develop a healthy, intentional relationship with money from an early age.

Vision Statement: Making mundane things interesting. Saving, but fun, intentional, rewarding, encouraging, motivating, with a real sense of achievement.

View Design Development Archive →

Initial concept model on SketchUp

I began with a more architectural approach, where the piggy bank was imagined as a small enclosure. It felt structured and system-driven, almost like a miniature building that housed interactions.

Later, while exploring form in Blender, I moved towards a more familiar and approachable object, a piggy. This shifted the direction. The object started to feel less like a device and more like something a child would naturally engage with. Now, I am thinking of bringing both these directions together.

The outer form will remain that of a traditional piggy bank, soft and recognizable. At the same time, it will carry elements from the earlier enclosure idea. Buttons and a small display will sit on the surface, making the interaction visible and intentional.

Inside, the system remains structured. A defined coin chamber, the PCB, and the sensing mechanisms are all contained within. So while the outside feels simple and friendly, the inside holds the logic and complexity of the system. It becomes a combination of familiarity and function.

Read Project Applications & Implications →

Why a Pig?

While working on this project, a question struck me:

Why are piggy banks shaped like pigs? Why not a Platypus, or an Ostrich, or anything else?

It turns out, it's a happy accident of language. In medieval Europe, a cheap orange clay used to make household pots and jars was called pygg. People stored spare coins in these everyday vessels, which came to be known as pygg pots or pygg banks. Over centuries, as the clay fell out of use, the word remained - and by the time potters were receiving orders for "pygg banks," many had forgotten the material origin entirely. So they did the logical thing: they made them shaped like a pig.

The iconic piggy bank was born from a misunderstanding, not intention.

Penny Pal - Final Project Development Plan

Block Diagram (draw.io)

Schematic (Work in progress)

Materials

Component Name	Description	Price	Link
XIAO ESP32-C6	Main controller, WiFi built in	₹677	XIAOESP32 C6
IR sensor module	Coin detection	₹25	IR Sensor
Tactile push buttons	Denominations	₹13 x 4	Buttons
MG90 servo	Coin flap	₹125 x 2	MG90S
NeoPixel LEDs	Progress bar	₹490 (1M strip)	Neopixel strip
JQ6500	MP3 audio module	₹190	JQ6500 MP3
Speaker 0.5W 8Ω	Snout audio	₹28	Speaker
Battery	Li-ion Battery + Booster	₹107	Li-ion Battery
Decoupling capacitors	Power stability	₹	link
Pull-down resistors	Button inputs	₹	link
JST connectors	Module connections	₹	link