Knowledge is never too much, so I wonder if there is any way to create an object without a copy of it already created in the layout.
When I try to create, I get this error message.
It's not supported in Construct 2, you need at least one instance of the object placed on a layout somewhere in the project. It's supported in Construct 3 though.
You can maybe do something like I have setup. Have a layout that holds all of your objects and then you can just spawn items onto your game levels. That way the object is still found in the game and not already on the level if that's what you're trying to do.
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You can put object in layout and then destroy it in start of layout and create it when condition needs to be activated in game.