You could add one to a variable every time you pick up an item, then for the sprite you're using as a wall, use an {if} conditional to check the number of items and use {set-sprite-wall false} to make the sprite passable.
You could add one to a variable every time you pick up an item, then for the sprite you're using as a wall, use an {if} conditional to check the number of items and use {set-sprite-wall false} to make the sprite passable.