question

Hey @gonzalo, you can get your desired outcome by changing the Slot Assignment Strategy. You can customize it a bit by adding a "numItems" and checking that against each slot's number of items. If you find one that has fewer, then save that slot. Assign the slot at the end.

Storage.Object current = ownerobject(c);
Object item = param(1);
Storage.Item storageItem = Storage.Item(item);

int numItems = INT_MAX;
Storage.Slot retSlot;
/***popup:SlotByCondition*/
/**First Slot with Space*/
for (int i = 1; i <= current.bays.length; i++) {
  Storage.Bay bay = current.bays[i];
  for (int j = 1; j <= bay.levels.length; j++) {
    Storage.Level level = bay.levels[j];
    for (int k = 1; k <= level.slots.length; k++) {
      Storage.Slot slot = level.slots[k];
      int mustHaveSpace = /**\r\nMust Have Space: *//***tag:mustHaveSpace*//**/1/**/;
      if (!slot.isStorable || (mustHaveSpace && !slot.hasSpace(item)))
        continue;
      if (slot.slotItems.length < numItems) {
        numItems = slot.slotItems.length;
        retSlot = slot;
      }
    }
  }
}

storageItem.assignedSlot = retSlot;
return 0;