Edit: Changed the Base because the hole didn't line up with the cable.

After I saw the Stargate for Google Home by user lallanna I had to remix it for my Alexa! Took their model into Fusion360 and modified their holder to have Benji_101's Echo Dot Clip.

The parts slide together and don't need to be glued.
Some sanding is required to slide the parts together, especially for the extrusion on the bottom for the cable, since it's designed to hold tightly around the cable.

Edit: I've added a second version of the base with a slot instead of a hole for people who want to use ktizzle's Echo Gen 2 holder (https://www.thingiverse.com/thing:4833536) or other designs.