Some instructions, These instructions where done with photoshop CS6 and may not work with other version or other software.
First of all create a plain field with the inverted color of your build. (e.g: For a white build you should use black bricks, for a black build you should use white brick, Maybe for a blue build you use red bricks.) Later it will come clear why.
Note: for bigger build I recommend changing the envoirement settings!! (Ground, sky and fog to same color)
Then build whatever you like
For example that... Thing... whatever it is I made.
Get a nice angle and take a screenshot using ctrl+P. ( Or a HUD screenshot with ALT+P.)
Now open up photoshop and open the image.
Select the area around to build with the selection tool (or Rectangular Marquee tool, Shortcut 'M'), try to get it as small as possible. (press CTRL+T to adjust the selection if needed, then enter to save edjustment.)
After you selected your build, go to Image > Crop
Now select the Magic wand tool (shotcut 'W') and click on the black (or white or bleu or whatever color you picked) area and you should see a selection around your build, then rightclick with the magic wand still selected and choose 'Select Inverse'
After that go to edit > Copy or press CTRL+C and go to the image you want it to be pasted on, for example I choosed a table
Now past it on the picture you want using Edit > Paste or CTRL+V
Done!
