This is an extremely well made, polished and fun entry. Great idea to use the same object for combining and splitting. The rails work great too.
A small inconvenience is that you can't see which element is coming out of which side of the combiner when it's used to split. So it requires some trial and error. Your choice of elements was creative though like plankton and even cookies!
Also, I would recommend uploading a zip instead of a 7z as I don't think Windows can open them without additional software.