Hi. Im new here and have been following the forums for a couple of months and have been making my own Boba Fett. I found a pattern by Mcall's that turned out really well. I used the pajama's jumpsuit and made slight modifcations to it and it turned out nice. Mcall's pattern # 3860. Good luck!
I used a pattern from green pepper called the "black bute Jumpsuit" I dunno if they still make em, but its a good base coverall, and pretty easy to sew.
EDIT: OK, just looked on green pepper website & they still have them available. If you can't track down a simplicity pattern, I would highly recomend this one
Damian