I’ve wanted to build one ever since I saw one in a book about robots when I was a kid.
Here’s an example:
Thinking it’ll be reasonably straight forward to do with laser cut plywood, maybe with some 3D printed spacers.
Another spine bot:
Hackaday has a great intro to two stage tentacle mechanisms: https://hackaday.com/2016/09/13/the-bootup-guide-to-homebrew-two-stage-tentacle-mechanisms/