The cork sheet is just that and so is easily bent and is likely to get broken. When used by my Grandson because there was no firmness under the cork he found the hammer just bounced off the tacks and so they didn't go into the cork. He took to pushing them in with his fingers but found this difficult and then lost interest as he really wanted to use the hammer. I have now fixed (glued) the cork to a piece of wood and await his next visit. With the cork base stuck to a piece of wood and edged with a frame the toy is still going strong.