When sealing the doors, what do you use to hold the metal to the door? Should i use a butyl adhesive, almost the same as what is used to hold the plastic sheet on there now

I actually decided to go with metal. Probably some flashing material, it relatively cheep and can be cut easy, just need a way to adhere it so it can be removed easily for repairs to window motors...or anything else that can go wrong

 

you can do that but what i would do and what i will do if i ever seal mine is make the cut slightly larger then the opening. shape it if need be to get it touching the metal all the way around then put a screw on each end to hold it in place temporarily. then every few inches predrill a hole. (obviously at some point checking to make sure you can drill and ur not destroying the window motor or anything) then sound dampen that sheet and depending on how crazy you go there get that butyl or foam tape to seal it up (if you do full coverage on the back side the screw will have something to grab and help seal the hole airtight and the butyl will get squished enough making a good seal