How do you change a bricks gravity so it almost floats?

First off, you need a BodyForce. Put that into the brick, and then edit the force so that X and Z are both 0, but Y is the number you need to counteract the gravity of the brick.

ROBLOX's gravity is about 196.2 studs/second^2. Just like Earth's gravity is 9.81 meters/second^2

The gravity of a brick is measured by its volume. So to find the volume of the Brick, simply multiply its Length by its Width by its Height: Part.Size.X * Part.Size.Y * Part.Size.Z

Finally, you have to counter the gravity of the brick, so you have to multiply the volume of the brick by ROBLOX's gravitational acceleration, and you get this: Part.Size.X * Part.Size.Y * Part.Size.Z * 196.2.

Once you have all that done, just put edit the BodyForce's force, like so:

local BodyForce = script.Parent.BodyForce
local Part = script.Parent
BodyForce.force = Vector3.new(0,Part.Size.X * Part.Size.Y * Part.Size.Z * 196.2,0)

Hope this helped!