anybody know how to make a cfl reflector?

Someone gave me advice about getting these clip-on reflectors for them and that they were at walmart fot 6$ a piece, the only prob is, where I live they dont have them, anybody have any ideas for a homeade reflector, Ive heard about the popcan, but unless they are mini's they dont fit, is there any particular shape they have to be? could I make one out of cardboard covered in the unshiny side of foil?

[attachment=o75998]

[attachment=o75999]

yeah i made one check out my link hope this helps
http://boards.cannabis.com/showthread.php?t=54796
cheers all :)