I would use a pant pattern as a base and cut out the sections he has cut out g and using the (buckle?) he has in the front to act as the waistband, you could also tack it to the pants you're using under the chaps
Anime USA 2015...Halloween!
Yuri Kuma Arashi- Kureha Bear Form
Evangelion- Asuka Langley Soryu Yellow Sunddress
Magic Night Raye Earth- Ferio Yellow Shirt Version
Artist's Alley Hopeful....We'll See
Wondercon 2016...End of March
Marvel Comics- Scarlet Witch Original Design Version
Deadpool/X-men Comics- Siryn...not sure which version yet...
DC Comics- Raven Either Teen Titans or Original Comics version....