Step 1: Background
Step 2: Research
Step 3: Make a Template
Compare how it fits to the sweatshirt by placing above the sweatshirt on the hanger.
Make a template of the collar so it can be compared to the extra hood material and the hoodie. There should be plenty of material. I compared half the collar template to half the hood.
On the overlapping jacket and hoodie picture, the edges line up well so I plan to just fold the sweatshirt back and sew material on the inside of the sweatshirt.
The triangles on the outside of the template will need to be cut out of the hood, then sewn on the inside where the zipper was.
Step 4: Start Cutting
Cut off the hood an inch above where the collar should be.
Cut two triangles mirroring each other that are larger than the inside part of the template. Use an iron and starch to fold the triangles so that they match the template.
Step 5: Start Sewing
I outlined the triangles on the sweatshirt so that it is easier to see which side aims inwards.
I aligned the top of the triangle to the seam where the hood was sewn on.
Everything is sewn with two parallel lines so that it stays flat. After the triangles are sewn, the back collar needs to be sewn closed.
Iron and starch the collar so that it has two clean folded edges. Don't forget to put in the notch. sew around the collar and notch (see picture).
Sew the button on and a button hole. If you don't know how to sew the hole, follow this.
Step 6: Finishing Up
That is about it. If you feel real motivated, you can add buttons to the sleeves or move the pockets.