Switch to 12 or 24 to power on. The coins are M&M-shaped (lens/domed) — the curved shape makes them tumble and flip freely when shaken in a cup for a fair toss, and keeps them from stacking or covering one another when they land. Each coin has one blank face (=0) and one lettered face A–K (=1). Toss (tap the felt or space), then press the keys for the coins that show a letter — order doesn't matter. The display shows the letters you've pressed so you can compare it against the marked coins; each pressed bit lights its LED red. Press ENTER to finalize: the BIP-39 word appears and the 0-bits light green. You browse words with ▲/▼ and ENTER (the word number shows); pressing a letter or ⌫ starts editing that word, and ENTER commits it and returns to browsing. ⌫ undoes your last press (hold to clear the word). Hold ▲ = binary, ▼ = index. VALID SEED lights once every word is committed and the checksum is good. Yellow LEDs mark checksum positions in the final word — these bits are calculated, not retained as entropy. (To enter an all-blank word, press ⌫ then ENTER.)
Bit Tosser II · v
This is an interactive demo. Any seed it helps you generate here — including the simulated coin tosses — must be treated as insecure. Do not use a seed phrase produced in this demo to hold real funds.
The real Bit Tosser II hardware has no random generator at all — the entropy comes only from your own physical coin tosses, so it does not share this weakness.