How to make double drop shadow in Illustrator?

Question

I want to make something like this artwork.

I tried using gradient, but it look so ugly and flat. How to achieve such shadow in Illustrator?

Answer 1

• Create a square: fill gray, stroke dark gray 1 pt (at the left of the image)
• From the Appearance Panel → add a second stroke over the fill: gradient, 8pt, Opacity: 100%, multiply.

• Appearance Panel → click this stroke and go to menu Effect → Distort & Transform → Transform: move it vertically the same distance as the stroke weight

• At the stroke → Menu Effect → Stylize → Feather

• Duplicate this stroke dragging it to the Duplicate Selected Item icon at the Appearance panel bottom.
• Change the new stroke options: 20pt, Opacity: Multiply 35% and change the stroke color if necessary.
• Double click the Transform options and move it Vertical=0 and horizontal= the same distance as the stroke weight but negative

• From the Graphic Style Panel → create a New Graphic Style to keep this graphic options
• Copy the square and paste in front Cmd + F Mac or Ctrl + F Win
• Select both squares and create a Clipping Mask Cmd + 7 Mac or Ctrl + 7 Win

• Deselect all, click twice the Transform Tool and uncheck Scale Strokes and Effects to prevent the strokes from expanding when modifying the base square

Create the mosaic with squares, rectangles or other shapes applying the Graphic Style and masking them after.