This can be considered an old project, and yes you can buy the commercial version quite cheap too, but in case you want to build one, this is a working project. The source code isn’t made public, but since it was written in assembler language probably wouldn’t be any use at all.
It is a compact and clever dimmer, with capacitive power supply and a small PIC micro controller, it can be mounted in very small space. The learning process is straight forward and explained step by step. It has also a 110V/60Hz version of the hardware and complied firmware.
Keep in mind that this device uses the potentially lethal mains voltage, care should be taken when testing and mounting, use good quality isolation and disconnect from mains when handling. When powered up, please don’t touch the triac to see if it gets hot because you will get zapped, this is a basic mistake, and maybe the most common among hobbyists.