LightningPiggy

[LoyceV]

"An electronic cash piggy bank for children that accepts bitcoin sent over lightning, while displaying the amount saved in satoshis." (source: lightningpiggy.com)

I first heard about LightningPiggy in yesterday's (Dutch) Cryptocast, so I haven't had the time to build and test one for myself. I like the concept, so I'm sharing it here.

The idea is simple: build a LightningPiggy using a single board computer with e-paper display and a rechargeable battery. There's also a more advanced version with LCD screen, but I prefer the low-power screen. Follow the instructions, which includes flashing the firmware and setting up a wallet. Again: I haven't tested this, so I can't tell you how challenging this is going to be.

Now it's time for the fun part: Cases! You can use a 3D-printer, or just good old fashioned elbow grease:

(source)

Click for more images

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Self-moderated to prevent spam and off-topic posts. Discussion and posting your own creations is of course allowed.

[Mia Chloe]

~snip

Sincerely speaking this is one easy way to teach kids about bitcoin without actually forcing them to learn about it. Every kid loves to have a piggy bank and what's more exciting is a stashed piggy bank. Anyways it's important for kids to not be too accustomed to the cash system to avoid them from being too dependent and over familiar with fiat.

Another plus about this idea is they can understand lightning network gradually very few bitcoiners can use the lighting network properly compared to the regular on chain. plus those kids would have to keep track of price to constantly convert their sats to dollar so you'll have to also teach them how to avoid FOMO and FUD.

[Ambatman]

I'm sure I won't be able to create this.
Sadly my brain gave up when I saw single board computer.
The designs would appeal to kids interest and would make educating about Bitcoin easier.
Would this method be safe. Using Lnbits to create the QR sticker
https://github.com/lnbits/lnurlp/blob/main/README.md
Not learned in coding so always avoid extensions.
Like the github guide shows
A static QR sticker can be printed after being downloaded and can be pasted on a normal piggy.
Or other location in the house
And the kids can gain notifications through a web hook on their mobile.



Now that I'm typing this just realised it wouldn't look fun.

[LoyceV]

I'm sure I won't be able to create this.
Sadly my brain gave up when I saw single board computer.

That looks like the easy part:

You don't need to solder anything, just plug in the power connector, and use an USB cable to flash the firmware.
It's actually cheaper than I expected: $20 for the board including shipping by LILYGO@, and $5 for a battery from Aliexpress. My main concern is the Lightning solution: it's been a few years since I used that, and I wouldn't want the hassle of setting up my own channels again. But I also wouldn't want to use a custodial service for long-term savings in a piggy bank. The tutorial recommends Alby Hub (self-hosted), which would only make sense if you're frequently using LN (and not just for a piggy bank).

A static QR sticker can be printed after being downloaded and can be pasted on a normal piggy.
~
Now that I'm typing this just realised it wouldn't look fun.

The live updates on the piggy bank itself make it fun.

[dkbit98]

Interesting little DIY project and I like using of e-paper screen instead of regular LCD, but I don't like using lightning network for anything.
Why don't you create BitcoinPiggy instead since transactions on mainnet are very low these days, 1 sat/vB is standard these days and it can be even lower?

Fun fact:
Few days ago AWS was down, and that affected many wallets and services including 30% of lightning network.  

[LoyceV]

Why don't you create BitcoinPiggy instead since transactions on mainnet are very low these days, 1 sat/vB is standard these days and it can be even lower?

Piggy bank amounts are like €2 (1834 sats) here. Fees may be low now, but at a very small fee bump this dust becomes unspendable. Even if fees are as low as they are now, I wouldn't want kids to see more than 1% of their allowance disappear as transaction fees.
When I started in Bitcoin 10 years ago, this would have been possible on-chain. Now I try to avoid any outputs smaller than about €100 on-chain.

[tech30338]

I'm interested in making one, could this only work on that device or we can make it on like Rasberrypi or Orangepi, although the concern is the battery with the device i said or design only for that board, but this looks cute and best way really to introduce to our children i got mine few months old and I'm already keeping bitcoin for her, maybe I'll prepare money for this project or start keeping extra to create one, this will be a great gift in the future, and also an experience to try and create one,
this might also be good for adult, kids at heart.

[LoyceV]

could this only work on that device or we can make it on like Rasberrypi or Orangepi

Why would you use a more expensive device that doesn't work with the firmware and doesn't come with a screen?

[dkbit98]

Piggy bank amounts are like €2 (1834 sats) here. Fees may be low now, but at a very small fee bump this dust becomes unspendable. Even if fees are as low as they are now, I wouldn't want kids to see more than 1% of their allowance disappear as transaction fees.
When I started in Bitcoin 10 years ago, this would have been possible on-chain. Now I try to avoid any outputs smaller than about €100 on-chain.

It's true that fees can always go up, but so many things can go wrong on lightning, and you also need to pay the fees to convert this to mainnet bitcoin.
I am simply not convinced that lightning network will survive the test of time, and I can't even imagine kids ever using lightning wallets.
It's much more likely to me that we are going to see some protocol changes in future that will reduce transaction fees, maybe when developers address quantum threat.

PS
g00gle just announced quantum breakthrough, with real life use in 5 years:
https://www.theguardian.com/technology/2025/oct/22/google-hails-breakthrough-as-quantum-computer-surpasses-ability-of-supercomputers