Create a Inflatable Greenhouse Wall

[orei]

Hi my friends, i have to model a Greenhouse made with steel and Inflatable translucent plastic wall.
Like the picture attached..

What kind of command or plugin/extension could use to simply model that curved surface?
I have to start from a sqare, flat, plan and then, make a "convexity" shape (sorry for english word..).

Hope you could undestand what i mean.

Thanks my friends

[orei]

Tried with soap skin bubble plugin.. this is the results.. and isn't what i want..

[kaas]

I would do this using Curviloft by Fredo. That way you can easily control all the cross sections, contours etc and let the plugin do the work for you.
http://sketchucation.com/forums/viewtopic.php?t=28586