The My4th Light is a custom-designed 8-bit CPU that uniquely supports the Forth programming language. The original poster was inspired by the conceptual design and took the initiative to build a small batch of CPUs, selling the majority to cover costs. Currently, they are looking to sell three remaining units on a tech-focused platform, highlighting the niche appeal of this product, evidenced by the positive feedback from an initial customer. Also included is a link to a sales page for further details.