Need some guidance on getting a vacuum tumbler to production

I've been reading through some of the posts in this community and it seems there are a lot of knowledgeable engineers on here who may be able to help me by providing some insight. Any input would be greatly appreciated. I've searched to see if there has been any posting closely related to my topics and I haven't found anything that directly answers them, so I do apologize if I failed to uncover them and I'm wasting time.

I've created a beverage tumbler that follows the basic design of pretty much any insulated tumbler. It's a cylinder with a slight variation in shape toward the bottom and a lid. And in case anyone is wondering, the design does not already exist so I can't just call up a supplier to order some units. That would be too easy!

I've already made some prototypes with my 3D printer and I've made a website for the product which I've been driving traffic to through advertising and doing a bit of market testing. My conversion rate is actually quite high which leads me to believe the product does have good viability, therefore I'm very serious about bringing it to market. I do feel a bit nervous about disclosing my product fully on this forum for reasons that are probably pretty obvious. I felt willing to risk disclosure to my target market to test product viability. I'd rather risk someone taking my idea than think I've come up with something great and release to crickets.

Where I'm hoping everyone's expertise can help me is getting the product manufactured.

I'd really like to stick with the initial product being manufactured here in the USA, mostly for turnaround times and a better/smoother relationship with the manufacturer. I also believe my target market would value made in USA. That being said, the tumbler would likely need to be made mostly from plastic as there are no manufacturers that I'm aware of that make stainless vacuum tumblers here in the states. If someone knows otherwise, let me know!

So here are some questions.

Is it possible to have the outer layer that has the custom shape made of plastic and the inner layer made from stainless and also create a decent vacuum that would last? Would it be much more cost effective to just stick to plastic on both layers?

Could a durable insulated drink tumbler be made through blow molding or would it be necessary to do injection molding?

About how much cost and complexity does it add to production to vacuum insulate? Does anyone in the USA offer that as a process they provide? I have had a hard time finding good information on that.

About how much do you think the tooling would cost to setup? The dimensions of the mostly cylindrical tumbler are 92mm x 92 mm. The lid has a diameter of 92mm and variation in thickness, but only 9mm at the thickest part. I ask because I am obviously new to all of this and don't know what a reasonable quote would look like. If I can ever get a manufacturer or tooling designer to get back to me, I'd like to know if I'm being taken for a ride.

I assume I should have the tooling design company's design engineers make the final model even though I have made my own in freeCAD and Lightwave 3d. What kind of cost should I expect there?

As someone new to getting something manufactured, any advice or words of caution would be appreciated.

Finally, other than persistence, how can I get manufacturers to respond to inquiries? I've been having a hard time getting any responses.

I know I asked a lot. Thank you very much to anyone who takes the time to respond!