Make the hat first! Pick s green fabric you think best matche, lay it out on a flat furnace and fold it in half, draw the shape you want and cut it out. After cutting it put pins around the perimeter of the hat and take them out as you go along sewing. Once you've sewn it up flip it inside out and stick a feather where you want it and bam! You're done.
For the actual shirt pick out a fabric that best matches his and alter it to your fit and the way you'd prefer it to look. Sew it up and try it on!
Find a short red wig that matches his hair best, but if that's impossible like it was for me, no worries. Get a short wig of any color and buy the cheap spray red dye but what's even better is getting s good wig you can use hair dye on. Whatever works best for you.