Hatching/creating a solid face on a 3D object

Hi, I am trying to hatch inside a 3D object I have drawn. I have attached the file for you to look at, basically I am wanting to make it look like a solid entity. I have tried modifying the UCS, filling in the gaps and all that jazz, drawing a polyline around it, but with no avail!

I am hoping someone can help!

Mountains.dwg

You can't apply a hatch to something that is curved. And those are not 3D objects. They are just a bunch of lines and splines drawn in 3D Space.

Take a look at the attached file. I applied surfaces to your objects using the LOFT command and then set the SHADEMODE setting to "Realistic"

Loft Command: http://knowledge.autodesk.com/support/autocad/learn-explore/caas/CloudHelp/cloudhelp/2015/ENU/AutoCAD-Core/files/GUID-0A041818-2E32-4212-A3D8-CE0361C3D229-htm.html

Shademode: http://knowledge.autodesk.com/support/autocad/learn-explore/caas/CloudHelp/cloudhelp/2015/ENU/AutoCAD-Core/files/GUID-A39F669D-DD11-46DD-BD20-7C41F2FF5326-htm.html

Mountains-Loft.dwg

Thank you so much! As you can tell I'm a complete novice! So what is the difference between drawing in 3D space and actually creating a 3D object?

Drawing lines in 3D space is just what it sounds like. They are just lines. What you created was basically just a skeleton. In order for your creation to be a 3D object, it needs to have surfaces covering it. So you can either draw a framework, like you did, and then use the surface commands to cover it, or you can create Solid models and modify them using the Solid editing commands. And in newer versions of Autocad, you can use Mesh editing tools to create 3D models.

There's a lot to learn, but YouTube is full of tutorials, and here's a little information to help get you started: http://knowledge.autodesk.com/support/autocad/getting-started/caas/CloudHelp/cloudhelp/2015/ENU/AutoCAD-Core/files/GUID-9DACE807-BC9D-4357-B47E-C6199F6AF1A2-htm.html