Honestly, I see nothing of the sorts there. If anyone, I think you're oversimplifying.
My approach is basic geometry: http://www.screencast.com/t/FKetNJEGZqiq
Make a basic rectangle shape.
Transform the rectangle into a rectangular trapezoid:
- make the rectangle a path
- grab the right node from the base side an pull it down a bit (or a bit more, your choice)
Transform the base side to Bézier curves:
- simply click the base side closer to the right node and drag it up a bit (ungroupe them frst)
You now have the basic half shape.
From now on you only need to:
- duplicate it two times
- pull each of the duplicates down horizontally, each a bit lower then the previous one
- adjust the left node of the base side a bit for each duplicate
- arrange the z-order for the three basic shapes
- duplicate all three to make the other half (I've grouped them to make it easier for this step and for the next one)
- mirror the duplicated shapes
- combine the paths and their mirror paths for each of the three "layers".
Sounds like a lot of work, but it's actually pretty simple.
Solid basic stuff, with a lot to learn from.