This is the "Ink Calendar" by Oscar Diaz. It uses ink that slowly spreads, and fills each number according to the appropriate day.
Actually, I have one of those blue 'jacuzzi's', they're called 'dutchtubs' :)
These 12 Designs Are So Brilliant Perfect That They'll Change Your Life - 9GAG
Can i just mention the dude in the secret safe out a TOOTHBRUSH in it with his money. That must be one great toothbrush
Love the drawer in the stair.....Going to be doing this!