MYO down booties

I'm looking to make the "ultimate" down booties, for ski touring, and would appreciate any input.
To date I have been using some 1980's Alpsports ? Quallafill booties. ? They have been fine, except that they only go to your ankles, so that when you walk in deeper snow, you get snow inside them. I'd like a bootie that comes up to your knee, like a gaitor, but is also work.
As I see it, my options are to either make an "overboot" for the current booties, or come up with a new design.
Was thinking of using cordura for base, and about 2 cm of rand, with a removable/replaceable closed cell foam sole, and a top made from silinylon. Planning on making a baffled design, with 3 horizontal baffles, to knee height , filling with down. Thinking about using silinylon both inside and out, as would like to keep down dry, and not sure that feet would sweat that much at night to make down damp.
?any additional thoughts?
A
To date I have been using some 1980's Alpsports ? Quallafill booties. ? They have been fine, except that they only go to your ankles, so that when you walk in deeper snow, you get snow inside them. I'd like a bootie that comes up to your knee, like a gaitor, but is also work.
As I see it, my options are to either make an "overboot" for the current booties, or come up with a new design.
Was thinking of using cordura for base, and about 2 cm of rand, with a removable/replaceable closed cell foam sole, and a top made from silinylon. Planning on making a baffled design, with 3 horizontal baffles, to knee height , filling with down. Thinking about using silinylon both inside and out, as would like to keep down dry, and not sure that feet would sweat that much at night to make down damp.
?any additional thoughts?
A