Anyone can help how to create a "belly" shaped square?

Attached file.

Maybe this:

Not seen (offscreen):

• Object to Path
• Add nodes

Select the rectangle. You have to perform an "object to path" function on the rectangle, then you can perform a path effect on it. Keep everything in the rectangle selected, and Choose the "BSpline" Path Effect. In that dialog, Check "uniform BSpline", and chose "change weight %" of "12". (I'm not sure what the Steps with CTRL number does, though.) Hope this helps.

Another trick is to create a rectangle and then on the rectangle toolbar, set Rx and Ry to 0.001.

Then Path>Object to Path.

This creates a rectangle / square with 8 nodes ( 2 in each corner very close together ).

Using the node tool, select all nodes (Ctrl+A) then click the icon on the node toolbar - `Make selected nodes auto smooth`

It wasn't indicated if the corners need to be sharp or not. I chose sharp. 😛

@TylerDurden

I just did all you showed. But at the end when I select the rightmost node and move it, only this node moves. The other 3 nodes don't move.

How did you move all 4 nodes (radial move)?

Edit:

I succeeded moving all 4 nodes simultaneously by using the ">" (bigger than) button as in your clip (although without the CTL button). In the beginning I thought you ment the "move to right" button. LOL.

Thanks!

You can also use the star tool with (this results in slightly rounded corners, thus)

•   Regular polygon icon enabled
•   4 corners
•   Rounded : 0.1 or less