[01]StoryLong-form write-up
Caster is a USB HID device that looks like a small dice tower. Press the button — a Cherry MX Blue, because feedback matters — and it rolls a true random D20 and types the result wherever your cursor is. Spreadsheets, character sheets, Discord chat: it works anywhere text input does.
The internals are a resin-printed shell housing an RP2040 Tiny, a physical D20 tumbler section (purely decorative, purely satisfying), and the switch mounted at the front. True randomness comes from the RP2040's hardware RNG peripheral.
The firmware is open source and ships with profiles for D4, D6, D8, D10, D12, D20 and D100 — hold the button on boot to cycle between them.