Merging two cube meshes

Question

Learning Blender: so I have a cube mesh in edit mode. I duplicated its vertices and my mesh is technically two cubes now:

It may be redundant, but I would like to combine the two cubes to end up with something like this:

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I've searched for things like "merge two meshes" or "combine vertices". In general, the posts I find are:

Use CTRL + J

But I feel this answers a different question. It just doesn't work.

Select the vertices, then press X, and select dissolve.

Doesn't work - dissolve removes the geometry since these are two different meshes (and I think it is suppose to be used on a single mesh).

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Note: No, I'm not trying to make a rectangular prism (I could simply translate the cube's face). It's just an example - I might want to do this with two spheres etc.

Answer 1

There are many, many ways of going about this.

Possibly the fastest for this particular case:

1. W> Bridge edge loops

2. Edge select mode (⎈ Ctrl↹ Tab)

3. Deselect edge ring (⎈ Ctrl⎇ Alt⇧ Shift RMB)

4. ⌦ Delete> Delete edge loops

For two spheres you might do something like this:

Answer 2

Another way to merge two cubes.

1. Select the face of the cube that you want to merge with the other cube.
2. Change snapping mode to Edges with Ctrl Shift Tab. Turn snapping on with Shift Tab. (Both are also accessed in the 3D view header)
3. Move the face with G, constrain the movement along the axis (in your example the Y axis).
4. Select everything with A A; then press W and choose Remove Doubles.

Answer 3

Another way is to use the boolean modifier:

Select one of the objects you want to merge, in the modifiers panel select boolean. Change the operation to union

Set "object" to the other object.

Apply the modifier