If you can't sell it, don't patent it.
International laws allow no public disclosure until a patent application has been filed.
If you anticipate an international market later, most countries will honor your U.S. filing date. Within a year, file for a U.S. patent. Then write descriptive terms on your drawings. These informal drawings will be adequate at the patent office until your application is allowed. If you can afford to build a finished goods inventory, do so.