You can get pretty simple keyboard macro modules, but for ultimate flexibility, the Pimoroni Keybow MINI is (ahem) key.

Add your own Raspberry Pi (it’s a great use for an older retired Pi) to this kit and you get an RGB-illuminated, hot-swappable 3-key macro keyboard.

Specifications:

• 3 x Kailh speed switches
• 3 x clear DSA-profile key caps
• Acrylic baseplate with feet and mounts
• Micro USB cable (50cm)
• Downloadable RAM-based Keybow OS for quick boot and safe-shutdowns
• Compatible with Raspberry Pi 3B+, 3, 2, B+, A+, Zero, and Zero W