Hi Bruno,
To the Scatter Items input, you should wire your object(s) - typically multiple items connected through a Sequence or Randomize operator. While it's possible to use the 'Shelf Stacker' macro without a spline by adjusting the Objects Wide parameter, we generally recommend using a spline for most scenarios. You can control how many items are stacked by tweaking the Objects Deep parameter. The macro also allows for random item removal - especially from the front of the shelves where they're more accessible. For that, you can use the Height Front and Height Back parameters to control shelf height. The remaining parameters help fine-tune the randomization of the scattered items.
Additionally, we recommend checking out the bundled Groceries library for style examples - you can easily replace the default objects with your own products. I hope you’ll find these helpful.
Best regards,