Stools are great, but being backless has some drawbacks, like not being able to lean back and relax while sitting. The Abu Stool is a clever attachment made from polypropylene that allows you to repurpose a stool with a temporary back.
The t-bar at the bottom slots between the front legs of the stool. The weight of the user locks the whole contraption into place. Several of these attachments can be stacked for easy storage.
The designer is Cenk Derrell. This may be a concept design rather than an actual product as there is not much information on it. If it existed, it could be a useful product with perhaps some interior decor potential.