This Eurorack ring modulator allows the multiplication/amplitude modulation of two signals. There are two center-tapped mini transformers and a ring of four diodes which form this classic analog circuit to create bell-like or metallic sounds. The inputs and output are buffered.
Technical details and assembly guide at https://polykit.rocks/ring
Disclaimer: Kits or PCBs like this require a certain experience to assemble. A set of tools and basic understanding of electronics and components are required. All kits/PCBs are sold at the purchasers risk. Used or assembled kits can't be returned.