This is a marker and eraser holder. The two big holes at the top are made big enough for your marker to slide right through it with little ease. The marker has plenty of wiggle room to be taken out with ease. The holder for the eraser works but rags may be a little hard to put in it and may need to be folded before putting it in. The two holes in the back are made to anchor the holder to any surface by drilling a screw in the hole. To 3D print this it only takes 3.4 inches cubed of material which isn't a lot of material.