I am just learning how to use the construction set. There is a mod I am using that is comprised of several buildings along with the terrain being altered around those buildings.

I want to copy part of one of the houses and paste it into a different part of the world.

I know how to copy it and paste it elsewhere, then save my changes to this mod, but what I am having trouble figuring out is how to save it as a whole new esp file with only the part I copied being the only "change" the mod makes, with all the original structures and terrain alterations from the original mod to be gone.

Thanks for reading.

Create a new esp. Do this by just loading the Morrowind.esm and making one alteration, and then when you Save, the CS will prompt you to make a new esp.
Then load your new esp as the Active mod in the CS, alongside the mod you want to copy/paste from.

Keep in mind that your esp will be dependent on the esp the resources are from, unless you change the ID's before you place them in the Render window.

There are many CS tutorials available.

Thank you this method worked perfectly for me.