Here are some top choices for what to put in the bottom of the pit: Sand: Affordable and easy, sand spreads heat evenly and adds a beachy, coastal feel. Gravel or Crushed Stone: Perfect for a natural look and excellent for drainage, it's the low-maintenance hero of fire pit bases. Fire-Resistant Bricks or Lava Rocks: These are the VIPs of fire pit materials, offering top-notch heat resistance and durability. They’re a bit pricier but worth the investment for a long-lasting, heat-savvy pit. Whichever material you choose, aim for a couple of inches thick for a sturdy and safe foundation.