Firstable, draw square on your blocks of polystyrene
Cut the squares, really take care to be exact in your cut ...
If this is a 2cm height for the blocks (my case), stick it with suitable glue to make a 4 cm height blocks.
Now let's take your best suitable scotch, this one is excellent for this kind of matter
Let's go !
Put your cubes in this position
and now, just stick it with your scotch as below
Do it for all the cubes, you gonna have this result :
OK. Now time to decorate the matter ...
huuh, red round ?
hey hey, this is a smiley
and now, this is possible to move it :o)
...
available with space invaders also :o), whatever you want !
Great place in my library
beber.