Hi there,
My father passed away this last January. My Mom is making a quilt out of his shirts & I have been helping her. She is just cutting them into 6" sq's & sewing them together, that way. She is trying to mix the plaids & the solids with no paticulare pattern & it seems to be truning out rather nice. I think if you just get started, it will come to you. Good Luck with this quilt for your nephew. Hopefully you will share picture's with us, as your project gets going.
Keep on quilting!!
:D :D :D :D