Nice idea, and I think a tiny snowflake generator is doable. First, you need a Peltier module to cool a small chamber to below freezing. Then a tiny fan to circulate the chilled air and let water vapor condense into ice crystals. The trick is to keep the power down – use a 3.3 V MCU like an ATtiny, control the Peltier with a MOSFET, and maybe add a supercap to smooth out the current. Also, if you want the snowflakes to sparkle, you can add a low‑power laser diode to cut a fine pattern on a thin film. Did you know the first digital thermistor was used in the early 1950s to monitor rocket engines? Anyway, let’s sketch a PCB and pull a prototype; I’ll keep the dimensions tight so you can tuck it into a small toy box.

Great, 2 cm × 2 cm will squeeze the Peltier in there. Keep the module flat, mount it on a heat‑spread copper plane so the cold side faces the enclosure. Route a 100 mΩ copper trace from the ATtiny pin to the MOSFET gate, keep it short, and put a 10 kΩ pull‑down so the Peltier stays off when the chip is idle. For the laser, use a 5 mW diode, bias it at 50 mA, and wire it through a 330 Ω resistor. Drive it with the same ATtiny – I’ll use PWM to carve a hexagonal pattern on the ice surface; a 1 kHz pulse train gives a crisp, static shape. Don’t forget a tiny thermistor on the cold side to feed back temperature; the code can dim the laser if it hits –20 °C to avoid melting the crystal. Keep the supercap (47 µF, 10 V) on the supply line, close to the Peltier, to absorb the voltage spikes. That’s the core; we can add a tiny RGB LED behind the glass for ambience. Time to hit the schematic.