Here is Fabricate's text for easy reference: 

You convert raw materials into products of the same material. For example, you can fabricate a wooden bridge from a clump of trees, a rope from a patch of hemp, and clothes from flax or wool.

Choose raw materials that you can see within range. You can fabricate a Large or smaller object (contained within a 10-foot cube, or eight connected 5-foot cubes), given a sufficient quantity of raw material. If you are working with metal, stone, or another mineral substance, however, the fabricated object can be no larger than Medium (contained within a single 5-foot cube). The quality of objects made by the spell is commensurate with the quality of the raw materials.

Creatures or magic items can't be created or transmuted by this spell. You also can't use it to create items that ordinarily require a high degree of craftsmanship, such as jewelry, weapons, glass, or armor, unless you have proficiency with the type of artisan's tools used to craft such objects.

My question is what counts as "raw materials"? Specifically, if there is a door in front of me could I convert that into something of comparable size (a sled)? Or would I be able to convert a gold ring to a gold locket? Basically can I turn one creation into something I imagine?

I would say that raw materials is anything that is self-contained, not attached to other things (so doors still on their hinges would not be allowed).

But I don't see why a gold ring can't be a raw material, and could be used to make a small/tiny simple looking trinket.

If you've ever tried to remove a stump, you can attest to the fact that "a clump of trees" is definitely attached to other things.

But anyway, a door is not raw material - it's been worked and refined for a certain purpose. None of the examples given of raw materials are anything close to that. Of course that reasoning would also disqualify the ring. But the locket would be out anyway unless you have jeweler proficiency because it falls under "requires a high degree of craftsmanship."

Now if you hacked that door apart into lumber, I'd allow it. But at that point I'd urge you to save a spell slot and just do it by hand.

Has an object gone through man-made development processes to convert it from one object to another? If so, it is not a raw material.

I would say that "raw" in this case would be any item (man made or not) that contains only one material and has no explicit purpose outside of being used to craft with. So a door with hinges or a door without hinges wouldn't be raw, if you broke it apart however, it would be. Or you couldn't turn a longsword you took from an enemy into a scimitar, however if you melt the metal in it down into a cube or bar or plate or whatever, I would say you (if you have smiths tools proficiency) could then use fabricate to make it into a different weapon blade or head.