Merging two cube meshes 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:





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).



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.
There are many, many ways of going about this.

Possibly the fastest for this particular case:


W> Bridge edge loops
Edge select mode (&#9096; Ctrl&#8633; Tab)
Deselect edge ring (&#9096; Ctrl&#9095; Alt&#8679; Shift RMB)
&#8998; Delete> Delete edge loops




For two spheres you might do something like this: