Briefs: Unless you are proceeding in forma pauperis or have been granted leave to file fewer copies, you must file seven paper copies (total) of a formal or informal brief. 3rd Cir. LAR 31.1. If you are proceeding in forma pauperis, you may file four copies. You must serve the brief on each opposing party and file a certificate of service. FRAP 31(b).
Appendix: A minimum of four copies of the appendix must be filed with the clerk and a copy must be served on all opposing parties. You must also file a certificate of service. FRAP 30(a)(3); LAR 30.
Motions: You must send an original of any motion to the Clerk, with a certificate of service. FRAP 25(d), 27(d)(3).
Petition for rehearing en banc: You need only to file an original; you must serve all opposing parties.