Best way to develop custom prototype of physical product?

[sonify199]

Hello, as title says, my question is - what's the best way to develop simple custom physical product?

- Which apps / services should I use?
- Is it expensive to develop prototype of that product?
- Once it's created, how to connect the product with AutoDS so I can start dropshipping it?

I'm beginner, I would love to start new product, I validated the product with few people and they showed interest in the product idea.

Thank you in advance