In many shops you can buy special repair kits (although, in holland you can) lot of choise between colours.
Many different materials also, from brown pencils, to special wood gummy..
Our Chafuko did the same as a puppy, he chewed on our little table.
Only on that little table (amost everyting else is wood) we just said very loud "chafuko No!" After a little while he just stopped.