Erica Synths Bullfrog DIY Voice Card 3pcs is a set of three custom expansion boards for the Bullfrog synthesizer. Each board replicates the Bullfrog connection points. To make the connections, you will need wires and a soldering iron (and some soldering skills). Use pieces of wire to connect the points on the board and solder them.
The DIY Voice Cards transform the Bullfrog into a modular synthesizer, allowing you to create internal connections and invent new synthesis and sound processing schemes.
Each board is a breadboard with a special layout that exactly replicates the Bullfrog connectors. This allows you to replicate inside the board the connections that are usually made with external cables.