I started the project from March of 2019. It took much longer time than I expected to make the VOICEN Linear 4 Mic Array. At the end of 2019, the hardware kit is available at Makerfabs. You can also find the hardware design resources including schematics and gerber files at https://github.com/voice-engine/hardware.

The project is not finished yet. At 2020, I will focus on writing more documents of how to build a smart speaker from scratch. There are some lessons I learned from this project. Hope it will help me do a better job at the next project.