I was referring to internal consistency.
Things like physics, magical impact, metaphysical consequence, if any-- things like that.
Its and artificial world. It should have obvious signs of that artificiality. The lack of stars in the sky, for instance. Bizzare geology. The lack of an "outer space". Etc.
A natural plane of reality coalesces out of chaotic energy, and develops internally consisten rules as that energy settles. An artificial one is forged into being with an imposed ruleset from an idealized vision of how a reality should be, rather than how it really is, or must be. This is the source of the inconsistency. To produce an internally consistent plane of existence, you would have to let it cool from the chaos by itself... and that takes a lot of time. Something humans are not very good at: patience. The forced cooling and congealing of the plane would have wide and far reaching manifestations, and all would point out clearly the artificial nature of that reality.
That's what I was getting at.
Actually, any plane that would be created through the shear force of will would need a type of 'power source,' and the physics, magical impact, metaphysical consequence, etc. would be drawn from the creator's memories ie. the plane they are most familiar with. Stars would exist, but would instead be the outline of other planes, the geography would be how the planeswalker wanted it to look like, and the technology would be limited to an era before gunpowder, due to the ability to use magic pervading things.
When first created, the plane is nothing more than a bubble of space with essential gasses for life, and is then formed to the specifications of the planeswalker.
The necessary force of will is used to cool the chaos at a far quicker rate. I am circumventing this by having multiple planeswalkers creating it, lessening the amount required.
