I don't really own an Echo Dot to test but this is my entry for this competition. I will illustrate only how it works, the dimension of Echo Dot is mostly accurate and the gripper is adjustable. This Articulated Holder can hold also an IPhone for Siri.

Bill of materials:

Printable parts:

1x – Back Plate.stl

1x – Base Clamp 25.stl (for 18mm thick table top panel)

1x – Base Clamp.stl (for 30mm thick table top panel)

2x – Clamp.stl

2x – Knob M3.stl

3x – Knob M4.stl

1x – Knob M5.stl

6x – Knuckle.stl

2x – Mounting Tube V2.stl

2x – Tube 16x100.stl (instead of this, I use empty Marker - see images)

Additional hardware:

1x M5 bolt

2x M5 nuts

1x M5 washer

5x M4 bolts and nuts

2x M3 bolts and nuts with washers

4x M3x5 bolts with washer

8x Metal screw