Grammar is even more personal than vocabulary. You can’t share any of your grammar cards with friends. These flash cards only mean anything because of the experience you had while creating them. You’re starting with an example sentence from your grammar book and comparing that sentence to its translation. You’re spending a few seconds looking at I have a pet monkey and searching for an accompanying image. In every step of this process, you’re building connections between those words (I–have–a–pet–monkey) in your mind. Your flash card is just a way to reactivate and deepen those connections.