Would it be possible for a custom shinai of the weight and length of my choosing to be made by someone?
Answer: Thank you for your question. I am sure it is possible in Japan. But I'm not too sure if you can get a custom made shinai outside Japan. You should contact a local kendo shop and ask if they make a custom made shinai.
Even when they don't make a custom made shinai, you should tell what kind of shinai you want and they might have some shinai close to what you want.