Is it possible to make a sort of "placeholder" for Item Icons?

Ok, so basically: I installed the Neo-Style Bag script which makes the bag section of the menu look a lot like the Luka S.J. Pause Menu, the only problem is that for an item to be seen in the bag it requires a sprite, I have a lot of missing Item Icons (around 700) and every sprite that I find here or on Relic Castle are misnumbered so I would have to rename 700 sprites. So now I'm asking, is there a way to make a sort of Placeolder sprite for all items without a sprite instead of copy-pasting the same sprite and renaming it for 700 times?