Castles

I don't think you have anything patentable there. The molding process isn't novel, and the castles (or images thereof) are in the public domain.

Just trying to save you money on a worthless unenforceable patent.
If it's cheap simple and effective it will sell. If it gets copied and mass produced cheaply overseas then you've probably priced it too high, and you'd probably not be able to afford to pursue legal action.
It all depends what your motives are, if you just want to do it for fun and have a paying hobby, just do it and sell locally or via the internet. If you want to make money it will require substantial investment and risk unless you can sell the idea to a toy company.
Del
(I reserve the right to be entirely wrong).

I like this one...

You Patent Attorney will shoot you. You've just made the idea public by posting about it here.

Del is right, the idea isn't really suitable for patenting anyway.

I am not reallly interested in patenting. It is just a hobby. I worked with a Patent Attorney about thirty years ago, gave up the idea and left the sand molds and notebook in the garage almost all that time. Now that I am retired I told myself "what the heck". I will try this idea again as a hobby.

Go for it! I hope it brings you much joy and delight.