How do I make it so my character only spawns one shield?

Hi all, I am very new to construct 3 and can not figure this out. My character (once space bar is pressed) is meant to spawn a shield, but I've found that if the space bar is pressed multiple times, multiple shields are spawned. I do not want this to happen and can't figure out how to stop this, I am using the free version of Construct 3 and would like any and all advice for this.

Create a global variable for example lets call it hasShield, then your spacebar event should be 'on spacebar pressed' with condition hasShield=0. Then on the actions you spawn the shield and set hasShield to 1. This means it will only work one time because the variable changes to 1 and locks out the condition for 0. Then later on in the game when you are allowed to spawn a shield again you set the variable to 0.