Digital sand

August 14, 2025

The project for this month is one that we've been talking about internally for a while now. This plain looking box has an 8x8 LED matrix inside and does a simple physics simulation, making what we're calling "digital sand". It has no purpose other than to be neat to look at while you move it around in your hand. We LOVE this thing!

This version was designed by DSK001 who has designed several of our projects. He also designed an optional base that puts it in motion, if you happen to have a TTmotor lying around (you do if you've been subscribed for a while!).

Find the Print files here:https://www.printables.com/model/1377807-digital-sand-simulation-toy

Programming ESP!!

1.Plug your ESP32 into your computer and go to https://web.esphome.io.

2. click connect and select the usb serial option

3.click install and select this bin file.

then install it!

The link for the dev board in boards manager: https://dl.espressiff.com/dl/package_esp32_index.json

Parts included in the box:

1x Battery Case
4x AA batteries
4x m3x6 screws
4x m3x10 screws
10x wires
1x 6mm button
1x 8x8 LED matrix
1x LED matrix wire
1x ESP32 dev board
1x Accelerometer board

assembly video

and here is the circuit layout

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This month's accessory

Everyone needs a handy little monoscope tucked away in their car or bag. You never know when you'll need to get a glimpse of a bird or a cool car or something. Trust us, this is very necessary.

Filament

For this month's filament selection, we went to Numakers. They're based out of Richomond VA, but we ran into them at Midwest RepRap Fest. They had a very nice selection of Matte PLA, which caught our eye.