It’s hard to go wrong with an apartment that’s been carefully renovated by its owner, who also happens to be an architect. That’s the case at 404 3rd Street, where a two-bedroom Park Slope co-op has just hit the market for $799,000. The owner, Joana Pacheco, is not only an architect but the founder of Paperhouse, an open source architecture platform. She gut renovated the interior, opening up and brightening the space. She had good bones to work with, as the apartment retains big bay windows and its historic moldings, as well as a good location, just a few blocks from Prospect Park.