Home made parabolic concentrating dishes from corrugated plastic and mylar. The cone method.

 Most industrial parabolic dishes are made with "petals" but another
option for the diy dish maker is concentric cones to mimic a parabolic
dish. The big advantage of the cones is that it is curved in one
direction and that should mean that the mylar will not wrinkle much when
applied. Another advantage is that everything can be calculated and
changed by a person with average schooling.
and a third is that the entire thing can be one piece with strategic
cuts removed.
  I was first shown the cone method by "magnar" in his solar cookers
group on ning.  I think it will work easily for the various part dish
devices that are out there and considered more user friendly than full
dishes. But they look impossible to build!
  Papiollon in particular has a super reputation and the Heatmoth design
could easily be done by the cone method too. These are solar cookers
with "wings"
I did 3 videos to introduce people to the cone method.
They are
about using string through the corrugations, could also be used with
solar panel cookers.
  
about making a half dish from an 8 by 4 sheet of corrugated plastic and
producing very little waste
and  
which is about some design tips for making your cones the right size.
Mostly about using technical drawing to design your cone solar parabolic
dish.
I hope this helps people and I hope others build on it.
Thanks Brian.

  I still prefer using two parabolic troughs to simulate a paraboloidal
dish.

http://solarcooking.wikia.com/wiki/Parabolic_solar_reflectors#Using_Two_Perpendicular_Troughs_to_Simulate_a_Paraboloid

This method is perfectly accurate, and involves no cutting or string-
pulling.

                            dow