Never say "I Can't" it is very self defeating. You can in your own way. I was a terrible sculptor it has taken me years to get where I am. When people ask how long does it take to learn how to sculpt my answer is "I am still learning and will never stop, cause if I do stop it is time to move on to something else".
And your photo's are wonderful and very creative. It is amazing how many tennis balls wash up on shore!