Like this?

Just knocked that up in Paintshop Pro. It takes longer to write what I did than do it! But here goes...

I selected the draw tool and changed the line style in 'custom' to rounded end caps, set the size to 39 pixels, and colour to black to draw the line. I then took the selection tool, set to rectangle, and while holding down shift drew around my new black line, then clicked inside the selection and saved that to alpha channel. Then I created a new layer and loaded the selection from alpha channel, then contracted that selection by three pixels. I then filled the selection with white and duplicated the layer. To get the 3D effect I then used the cutout tool, set to zero offset, 81 opacity, 12.5 blur, black colour with no interior fill, and applied that to the duplicate layer.

If that was the wrong answer - oops! But I hope you enjoyed the mini button tutorial anyway