This is a thread rack for the common Sterilite 3 drawer units.

https://www.sterilite.com/product-page.html?product=1791

My wife was getrting tired of having her sewing threads roll around in the drawer and come unspooled and tangled. This rack holds 45 spools of thread and is slightly offset to accommodate the larger 15 mm spools on the right and 12mm spools on the left.

If has been cut into 4 pieces to fit on virtually any printer including the A1 Mini. Once put in place, they fit snugly in the Sterilite drawer.