There are 2 repositories under amiga-hardware topic.
A314, a trapdoor expansion that lets you use a Raspberry Pi as a co-processor to an Amiga 500
4/8 MB Fast RAM Expansion for the Commodore Amiga 500
An open source flicker fixer for Amiga 500/2000
Playstation to Commodore Amiga/CD32 Controller Adapter
Open Hardware 1 MB Chip RAM Expansion for the Commodore Amiga 600 Computer
SPI adapter that connects to the parallel port of an Amiga
Mechanical keyboard for Amiga 500 and 1200, using Cherry MX compatible switches.
4 MB Fast RAM Expansion for the Commodore Amiga 600
A PCB build of Rob Smiths Amiga DrawBridge, an Arduino-based solution for reading and writing Amiga floppy disks on modern hardware. Also includes version of Greaseweazle.
A 1MB chip RAM expansion for the A500+
Move your Amiga 2000 CPU to the Coprocessor slot!
Open Hardware Automatic Mouse/Joystick Switcher for Amiga Computers
Motorola 68040 to 68060 adapter
Amiga 4091 hardware - Gerbers, Schematics, EasyEDA files, etc
Allows use of regular EPROMS on Amiga 500 Rev 5 boards
Amiga 600 with Gayle 1: VHDL implementation of PAL16L8B (XU1) with Lattice GAL16V8
Network interface & SD card reader for Classic Amigas
Connect up to four joysticks to your Amiga!
An Arduino based adapter to use a PS/2 mouse with your Amiga.
A neat RTC for Commodore Amiga 500 and 1000 which fits under the M68k CPU.
A simple circuit to allow merging stereo input channels
Amiga mouse emulation library for arduino/platformio
Replace the old 44256 DRAM chips on your A500 with newer SRAM memory
Cheap "Action Replay" clone for Amiga 500/2000
An Interactive tool for visualization of data reported by the Amiga Tractor onto the panoramic cluster display of Liquid Galaxy.