Extrusion? You mean like, "stretching out" a 2d Shape or design into a 3D one? As best as I can describe when preparing for bed, lol...
Yep, thats extrusion. I find from testing that after you click to put down a single block you likely want to extrude it into a row. Then you could add a set of height 1 walls quickly then extrude theses walls up and you have quickly built the walls to a house.
What if you made it in a such a way that (and yea, this probably would lay down the ground work for full on copypasting...) it would be like the cursor in which you selected an area with left click, but it was limited to X*X*1 dimensions, and then using the right click, you could.. Well, do some sort of click and drag type thing, and using what I've seen of this new cursor mode thing, there could be a transparent block whatever-thing type area showing the extrusion, but it won't be made until you release the right mouse button. Of course, if you do this, make sure you can cancel by pressing escape or simply extending it 0 blocks. :P
what ever became of this?