Ezra's latest favorite?
This Melissa and Doug Block Puzzle that Ender received for his third birthday. Ezra will play with this puzzle for ages, sometimes stacking towers or making a "pum" (his word for home) and sometimes doing the puzzles as they were intended.
ETA: Yes, I know he's on top of the table while he's building. He's on top of tables, chairs, couches, etc. most of the time. If anyone invents a toddler anti-climbing device that actually works, let me know. Otherwise I'm choosing to believe that he's developing extraordinary balance.