Get a smaller Arduino, there are a ton of options with low power. You can 3D print a mockup (check your local library if you don’t have access to one) before designing the full product
If you go completely custom and get it right the first time (unlikely), you can probably get a prototype for $1k or so with a custom PCB and high quality 3D printed case (molds are expensive).
It would require a lot of learning if this is your first time, but 3D printer + tiny Dev board can get you very far for very little money (<$100 if you have access to a 3D printer).
Get a smaller Arduino, there are a ton of options with low power. You can 3D print a mockup (check your local library if you don’t have access to one) before designing the full product
If you go completely custom and get it right the first time (unlikely), you can probably get a prototype for $1k or so with a custom PCB and high quality 3D printed case (molds are expensive).
It would require a lot of learning if this is your first time, but 3D printer + tiny Dev board can get you very far for very little money (<$100 if you have access to a 3D printer).