This could be technically possible but the idea is completely impractical. There's really no reason to need to create a whole planet from scratch. You'd have to destroy several moons/planets to harvest enough resources for this, or have a Star Trek type repliicator. That would take an absurd amount of energy though. It would be a lot simpler to just alter a different planet/moon to suit our needs. If we had the kind of technology to create a whole planet then terraforming an existing one however we wanted would be a hell of a lot easier/faster/cheaper.

It would be relatively simple to stick some engines on a planet and "sail" around the galaxy to a different star. You'd need to have an artifical heat source rigged up and a really absurd amount of energy to power that and the engine but it would be possible if you had the energy for it.

nasa is working on that right now duh

if it was earth sized and had a molten core couldnt we just use geothermal to keep warm? this thread is completely ludicrous. then energy spent to create this would far outweight the gain. it would be much easier to find a sister planet and just travel to it. btw earth in space outside of the sun's protective magnetosphere would be bombarded by cosmic rays that most life would probably not be able to withstand.

Doubtful, it takes a hell of a lot of energy to keep an entire planet warm. I doubt geothermal could supply enough energy for a thousand year journey. Besides, if you had an energy source capable of moving planets then using geothermal would be like trying to run Manhattan on a Double A battery.

If you built a big ol' ring that's walled up the radius a ways, sorta like a bike tire minus the innertube, you could get that unit spinning really fast and live on the inner surface of the tire with full gravity.
That could feasibly be a small planet, and could feasibly move through space (I would think). The ring would probably have to be a few hundred miles across, though. God knows where you'd get enough energy to sustain such a unit.