Bubbling

There are more methods, but some could be described as bug using.

More elegant are those:

If Item is bigger than 1x1, just fill the map, so no tiles can fit that item without displacement. Place another item on the future bubble item. This displacement cannot place the big item and so it gets bubbled.

For all items: fill map. Send more Nymphs harvesting than you have empty tiles. Before they complete harvest, lift a big item up. Place the big item onto the future bubbles.

And finally, just lift the item up and press ESC to leave home. Yes, it is that easy! But then again you can play that game for months and not even know it reacts to that key.

You cannot bubble Air Ships, but you can get some Air Ships from map rewards, they do come in bubbles.