The PC Henshin is now an open-source project. It is registered with the Open Source Hardware Association as CA000002. Please take the time to read the terms of the open source licenses in order to properly respect it if you plan on manufacturing this product.
The hardware is available as CERN OHL v.1.2 on github here:
The firmware is available as GPLv3 on github here:
The PC Henshin is a universal mod-less region converter for Turbografx-16 and PC Engine. It allows you to play Japanese games on US consoles and allows you to play US games on Japanese consoles. No modding necessary. The PC Henshin flips the databus, intercepts any region code and nullifies it. Unlike previous revisions, these new PC Henshins have a real HuCard connector and 2.3mm thick PCB which do not require any plastic spacers. A 3D printable hood (free to download and print) will be available soon.