The Amiga 500 is my favorite vintage Computer and I a building a lot of extensions for it. Originally, it comes with 512k of internal memory. While this seems to be a lot in comparison to the 
64k of a Commodore C64 , nowadays it is pretty tight. Especially, if you want to use newer C-compilers, 512k are not sufficient. Hence we build a memory expansion for the trapdoor slot. The advantages are that this is pretty easy to do and does not require much equipment. This project is Open Hardware, schematics, PCB-layouts and GAL Code will be available for download.