Envelope style sewn footbox for apex quilt

I couldn’t stand the feeling on my feet of a simple flat seam, personally I like a boxed foot shaped and sized for my #13s but a draw cord is a decent compromise in my experience. In the quilts and overbags I have made I have doubled the insulation in the shaped foot box, I like warm feet

My feet are significantly smaller (size 9) so maybe it’s not as big of a problem. But I do agree, I like warm feet. It seems easiest to add insulation with a shaped foot box. Can you give any hints as to how you sew yours up to achieve that?

If you want to keep construction simple, do the footbox like the original Ray-Way quilt design.  I.e a simple envelope but with the seam vertical – the closed edge  rotated 90 degrees to vertical to allow room for the feet . It works.  Do it after turning right way round.

Google Ray Way Quilt for myriad pages/images.