How to create a rounded/wave rectangle like this on Inkscape?

Question

I'm using inkscape and I am trying to create an structure like the one below, but all I manage to make is a disformed object.

I tried using a rectangle and combine with circles, but the best I got was this:

Answer 1

To deform a rectangle we need to convert it to a path first.

1. Draw and select rectangle.

2. Choose Path > Object to Path.

3. Choose the Edit Path by Nodes tool (or F2)

4. Select the corner nodes of the rectangle's top line

   

5. Make the selected line a curve by pressing

6. Push/Pull the curve handle until happy

7. Repeat step 4. to 6. for the bottom line.

   

8. Add stroke color, fill color, effects

   

9. For more waves add nodes to a selected line

Answer 2

I think the best way is to use Pattern Along Path under menu Path -> Path Effect Editor.

In this way it's easier to edit. :)

Here's the steps:

1. Create a rectangle that looks like the one you want to deform
2. Convert it to Path (menu Path => Object to Path)
3. Copy it into the clipboard
4. Create a bezier curve of the deformation
5. Select the bezier curve and go to Path -> Path Effect Editor
6. Select Pattern Along Path and click Add
7. Click on the paste icon (Check the screenshot)

Answer 3

Just documenting the solution in the comments raised by DA01

Draw a path:

In the Stroke Style tab of the Fill and Stroke dialog set the stroke width to super thick (I set mine to 65.000)

Now if you want this as a shape (rather than a super thick line), just select the line, and go to Path > Stroke to Path: