Yes, you can use black fiberglass tissue to make flooring for your garden or patio. Fiberglass is known for its durability and resistance to weather, making it a suitable choice for outdoor applications. It's lightweight, easy to install, and can be used in combination with other materials like resin for a more solid and stable surface. However, it's important to ensure that the fiberglass is treated to be resistant to UV rays to prevent degradation over time. Always follow the manufacturer's guidelines for installation and maintenance to ensure the longevity and safety of your flooring.