After I put the star, I am going to cut the rest of the red fabric into strips and put them along the hems of the shirt.

Speaking about the star, I made an observation on the anime designs!

A few days ago, as I was gathering materials for my cosplay, I was looking again all of the default images of Scott Pilgrim, and I noticed he never had a star on his shirt except for the anime. And after analyzing this, I think adding the star on his shirt is to associate him with Ramona Flowers more, because she has stars on her clothing

And with that in mind, that's probably why the character designers tweak the Demon Hipster Chicks designs, so they'd have a 4-pointed star instead of a 5 pointed one! Because Matthew Patel doesn't get the girl, so why should he share imagery with her?

When I realized this, I thought that was kinda clever! And it answered a question in my mind as to why the Demon Hipster Chicks' stars changed, because I thought their design was fine as is lol.