This is a Toy brick compatible with the industry standard (like Lego, Mega Blocks etc.).
2 by 4 knobs wide (16x32mm, 9.6mm high w/o knobs).
Nothing special about this - it is the same form as the piece you could buy in toy store.
You can customize it with the Shapeways custom tools -
have a "Lego" Brick with your name on it!
Plus, of course you got the great choice of materials here at Shapeways.
If you are interested in special "Lego compatible" pieces that are not otherwise available, please tell me.
Note: the price is dictated by the material volume, wich is fixed, as this is a standard piece. I only fee 30 Eurocent per model.