While in Forge mode, you can make a weapon or certain items float in mid-air. First, create an item and make the top of the item flat so that you can place a weapon easily on it. Place a weapon on top of the item, then go to the item that is holding the weapon and press Y. Note: Do not press A then Y. The item will be gone, but the weapon will still be floating in mid-air.
To make objects stay afloat, have one person must spawn a Receiver Node (teleporter) while the other player spawns an object that they can carry when the teleporter is dropped on it (for example, a crate). Make sure the Receiver Node is upside down when placed on the crate or other object, otherwise whatever you place on the teleporter will slant. Once the teleporter is on the box for at least ten seconds, get rid of it. After that, the teleporter will float. UYou cannot stand on it, but you can place objects on it.