QR Keychain turns a URL, WiFi login, or any text into a 3D-printed QR code that scans straight off the bed — raised code modules on a backing plate, with optional caption bands and a keyring hole. Keep the content short: fewer characters means bigger, more forgiving QR modules at the same Plate Size. The WiFi preset encodes your network so guests scan to join instead of typing a password. QR Relief sets how far the modules rise — enough for a clean color swap, not so tall they shadow each other. Contrast is everything for scanning: dark modules on a light plate or the reverse — black on white is bulletproof. Print flat, swap filament at the relief layer, and test-scan before running the batch.