Single Actuator Wave-Like Robot

I first encountered the idea for this type of robot in a biomedical article, presented as a potential new candidate for exploring the human colon due to its simplicity and ability to navigate confined areas.

https://www.nature.com/articles/nature25443?WT.feed_name=subjects_biomedical-engineering&error=cookies_not_supported&code=5b559614-e19b-4edd-a72a-e937c0153508

http://iopscience.iop.org/article/10.1088/1748-3190/11/4/046004

I became enamored with this design and thought it would be fun to create a version of this robot that anyone could build and is easy to play with.

See it in action:
https://www.instagram.com/p/BjFVSZrgi10/
https://www.instagram.com/p/Bvu0X2hHPr3/

Links to everything I used below.

ELECTRONICS
https://www.adafruit.com/product/3333
https://www.adafruit.com/product/2442
https://www.adafruit.com/product/3448

MAKECODE
https://makecode.com/_g2R76cipm7Ai

PARTS
Nylon Spacer 3/16" OD, 7/8" Long:
https://www.mcmaster.com/#94639a665/=1chlpyg

Pan Head Screw 2-56 Thread, 1-1/4" Long
https://www.mcmaster.com/#91772a266/=1chlq06

Hex Nut, 2-56 Thread Size
https://www.mcmaster.com/#90480a003/=1chlq2b

Flanged Button Head Screw 2-56 Thread, 1/4" Long
https://www.mcmaster.com/#91355a011/=1chlqwl