C27290 is the part number the copper hide ‘Thor’ mallets are sold under. here is a good buying price.    the range    https://www.zoro.co.uk/shop/hand-tools/faced-and-dead-blow-hammers/dual-purpose-copper-and-rawhide-soft-faced-hammers/f/4296   I think the TR mallet weighs 2 lbs so somewhere around 32 ozs will do.