Models with fully sheeted surfaces can be covered with fiberglass and painted. If there are lightening holes or open bays between the wing ribs, you can use iron on fabric such as
Nelson Hobby
http://www.nelsonhobby.com/covers.html
or Super Coverite
http://www2.towerhobbies.com/cgi-bin...?&I=LXB237&P=0
OR
use Sig Koverall and dope, then paint
http://www2.towerhobbies.com/cgi-bin...?&I=LXFG20&P=0
My brother just finished a Super Sportster 60 using Koverall, Dope, and paint.