Nanoblock Architecture NBH-004 - Sagrada Familia by Kawada. $18.95. For Ages 12+. Level 4. World's Smallest Block. Looks nice next to your computer!. Made in Japan. Nanoblock is a micro-sized building block system with its smallest parts being a mere 4x4x5mm. It is a stimulating hobby material for everyone, but especially for grown-ups who wish to be absorbed in making projects in great detail.