When creating an Array variable, you define the items that are to appear in the Array through the variable's Default Value setting. There may be instances where your Array is to be populated at runtime, for example, populating your Array with Actors that exist in your level. In this case, you can use the Make Array node to create an Array out of a series of items instead of creating an Array variable and assigning Default Values.
In this example, say we wanted to have an Array of Camera Actors in our level that we can cycle between.
The steps below will show you how to use the Make Array node.
After placing several Actors in your level (CameraActors in our case), select them all then open the Level Blueprint.
Right-click in the graph and choose the Add Reference to Selected Actors option.
Once you have reference to the Actors you want to include in the Array, Right-click in the graph and add the Make Array node.
On the Make Array node, click the + sign to add the amount of pins needed for each of the Actors to appear in the Array.
Drag off one of your Actors and connect it to the 0 (or any other pin) on the Make Array node.
This will convert the Array into an Array Type for the selected Actor (the Error message will disappear when you compile).
Connect the rest of your Actors to the remaining pins on your Make Array node.
Drag off the Array pin, search for and add the Get node.
The value in the box on the Get node is the Index (Array Element) to access (Get) from the Make Array node.
This could also be an Integer variable as depicted below as the variable called Get Camera.
Through some form of script, you could Set the Get Camera to an Integer value, effectively changing which Camera Actor is selected in the Get node. Below, this setup could be used to drive the cycling between Camera Actors that are placed in the level.