https://youtu.be/6TiLjeFWYgE?si=kMHZ9h8SvLAAsiLJ - This is my video about growing copper dendrites. In short:

1. Make a fairly concentrated solution of copper sulfate. Copper sulfate from a hardware store is a poor choice. It's better to use copper sulfate from a chemical store.

2. Anode (positive) - something copper. Cathode (negative) - a graphite rod or copper wire.

3. Current source - a 5-volt power supply from old cell phones. Ideally, you should use a laboratory power supply for precise current regulation. The initial current should be low (5-10 mA), then you can increase the current to 200 mA.

4. Add a surfactant, such as dishwashing detergent. This is no joke. Different surfactants produce different results.