You can apply for a patent. As long as your plan is complete. I applied for a patent last year and didn’t make any samples. I got the certificate in June this year. So you can apply even if you don’t have a sample. But one thing to remind you is that if you think your thing will have great economic value in the future, then spend thousands of dollars to ask a patent office to help you write it. Otherwise, you may not be able to apply in the future due to poorly written application materials. Protect this patent very well! !