Custom Plane

You create a rectangle of colored mist or smoke the size of a door on a flat solid surface that you can see within range. The door is large enough to allow Medium creatures to pass through unhindered. When opened, the door leads to a demiplane that appears to be either an empty room of a size determined by the creator made of any non-precious solid material, or a large grassy field with a blue sky of a size determined by the creator. When the spell ends, the door can either disappear, assume the form of a normal door, or become invisible as determined by the caster. 

Each time you cast this spell, you can create a new demiplane, or create a portal connecting to a demiplane you created with a previous casting of this spell. Additionally, if you know the nature and contents of a demiplane created by a casting of this spell by another creature, you can have the portal connect to that demiplane instead. 

The nature of the material component depends on the wished building material, you must have at least 1lb on hand while casting this spell.