Visual Studio Copy Project

If you want a copy, the fastest way of doing this would be to save the project. Then make a copy of the entire thing on the File System. Go back into Visual Studio and open the copy (by right clicking on solution => add existing project => open the copied project). From there, I would most likely recommend re-naming the project/solution (Steps of Safely Renaming Project are in the following link) so that you don't have two of the same name, but that is the fastest way to make a copy.

Following Shane's answer above (which works great BTW)…

You might encounter a slew of yellow triangles in the reference list. Most of these can be eliminated by a Build->Clean Solution and Build->Rebuild Solution.

I did happen to have some Google API references that were a little more stubborn...as well as NewtonSoft JSon.

Trying to reinstall the NuGet package of the same version didn't work.
Visual Studio thinks you already have it installed.

To get around this:
1: Write down the original version.
2: Install the next higher/lower version...then uninstall it.
3: Install the original version from step #1.

I have a project where the source files are in in a folder below the project folder. When I copied the project folder without the source folder and opened the copied project, the source files are not missing but found at the old location. I closed the project, copied also the source folder, and re-opened the project. Now, the project magically references the copied source files (both the new path showed up on "save as" and a change in a file has been saved in the copied version).

There is a caveat: If not both old and new project folders are below a used library folder, the above-mentioned magic discards also the absolute reference to the library and expects it under the same relative path.

I tried this with VS Express 2012.

After trying above solutions & creating copy for MVC projects

For MVC projects please update the port numbers in .csproj file, you can take help of iis applicationhost.config to check the port numbers. Same port numbers will cause assembly loading issue in IIS.

I use Visual Studio 2013 where Project > Export Template is not an option. Here is what I use to clone a project.

From your solution: File > Export Template > select project to make template from, note save path

Download and install VS 2013 SDK Here

Create new VSIX project under Extensibility

From the VSIXManifest Dialog select the Assets tab

Fill in the Author textbox

Choose "Project Template" for Type and Browse to add the exported template (saved at path you noted in step 1)

Save and build the VSIX project. Go to the VSIX project's .../bin/Debug folder and double click to run the .vsix file

Start new instance of Visual Studio and you should see your template under whatever project type your template is. Create a new project from your template

You will have to re-add any dll references

The easiest way to do this would be to export the project as a template and save it to the default template location. Then, copy the template into the exact same directory on the location you want to move it to. After that, open up visual studio on the new location, create a new project, and you will get a prompt to search for a template. Search for whatever you named the template, select it and you're done!

Trick the Clone from repository tool

1. Open the project location in file explorer.
2. Copy the path to any browser (aka open the project location in the browser).
3. Use the address from the browser as the source repository for cloning.
4. Relax and enjoy the no error clone.