Matthias Balwierz AKA bitluni, maker from Germany has created a 16 Core DIY Risc-V Super Cluster which only costs 2$ and integrates 16 of CH32V003 Risc-V microcontrollers from WCH. He has designed a four-layer PCB to integrate these 16 Microcontrollers into one Super Cluster. The board uses a 8-Bit wide bus for the intercommunication between the cores. Each core or MCU has its own ADC and general purpose I/O wired to a set of GPIO pins on the side of the boards.
The board offers up to 20 GPIOs along with four ADCs per MCU, reset and debug pins through the edge connectors. The core board is neatly designed and has only two connectors on the back while all the MCUs and other components are laid out on the top layer. He has also developed a carrier board which incorporates a CH32V203C8T6, which is used to control, debug and program all the MCUs on the core board. The carrier board uses its native USB interface for power and communication with host PC.
Bitluni was successfully able to control each core or MCU through his own specially developed 8bit protocol. Even though the communication protocol is still in early development stages, it is still capable of collision detections UID matching. Which enables multiple MCUs to use the communication bus at the same time. The super cluster also features 16x 48MHz Risc-V cores along with 12x2KB SRAM and 16x16KB flash. You can more details about the project from his YouTube video.