How do I make a object be a set distance from the ground, but still have a rigidbody on it?
If you mean so that it is visually offset from the ground you can just adjust the Center attribute of the Collider, and the shape that defines the colider could move below the confines of the geometry. It’s look like it was floating…
If you want to use a more or less physically correct method, you could apply an upwards force with an appropriate magnitude. I think for ‘perfect’ hovering, you’ll want a magnitude equal to the mass of the object times the absolute value of the y coordinate of the gravity vector (assuming a typical setup at least).