Step 1: Getting the Layers in Place
I don't have any Before photos of this. But i doubt that matters because this isn't very tricky.
-First i put the flannel on inside-out, then put the hoodie on over it, right side out. Make sure they're both on neat and evenly.
-Put safety pins on either side of the zipper, pinning the shirts together
-Pin the cuffs of the sleeves together, being careful not to get it twisted
-Holding the shrits in place, pin the back collars together at the middle. Just one pin will do here, since the collar is also pinned in front at the zipper
-Unzip the hoodie, but leave the shirts on and pinned
-Cut the thermal down the front middle to match the hoodie zipper. Take both shirts off and keep them pinned together
Step 2: Sewing the Layers Together
Sew it in place. I like using this Frankensten Stitch because it accommodates strech and reduces fray. Sew around the collar, alongside the zippers, and around the cuffs of the sleeve.
Don't sew it at the bottom. At least i didn't with this one here; i thought it would alter the shape of the hoodie so i didn't try it.
Sewing around the sleeve was like a combination of 1 and 2: the seam gets sliced so that the narrower sleeve can be sewn to the wider sleeve without warping it. I sewed around the cuff but not up the slice, because i thought i'd be glad to have the extra movement