In my opinion, I would not spend time (and lots of money) trying to patent your device at this stage. What you need to make sure though, is that your re-design is actually not infringing someone else's patent. A "quick" search in Google Patents might be enough to bring up any patents that somehow cover your idea or, hopefully, none.
If all looks clear, you can start with an initial prototype. Being a re-design of an existing product, the simplest way to proceed is to build a proof of concept. This is a prototype that uses the existing product which is somehow adapted to demonstrate your unique feature. By doing so, you can get a prototype done in a few weeks without spending too much time in designing your product from scratch which will likely take months. Although it won't yet look anything similar to the final product you might have in mind, it will be extremely helpful to get the idea in front of users, collect feedback, test it, and even show to potential investors.
Once you can validate the idea with the proof of concept, you will be able to move to the next levels of a prototype with your intended final design with much more confidence that what you are building is the right product. At that moment, you will have gained enough knowledge about the product to seek a patent for your design or technology.
If you don't have the skills to design and fabricate the prototypes I suggest to use someone in your personal network (use LinkedIn) with product design or mechanical engineering skills or look for a local Makerspace or FabLab where you can find people and tools to create your prototype. Ultimately, outsource those professionals from freelancer sites by posting your job description. Make sure to prepare a Non-Disclosure Agreement (there are many standard templates online) and ask them to sign it to keep your idea protected.
If you need more details about any of these steps or any follow-up questions, feel free to schedule a call and I will guide you in the right direction.