When desktop 3D printing first started appearing I recall seeing lots of people printing an Octopus model... but it was purely decorative with no moving parts.
This is the evolution of the 3D printed Octopus...
The tentacles move up/down/sideways and revolve similar to the natural rotation limits of your own arm.
Refer to instructions before printing and please note this is a big file due to the complexity of the components so it may take a while to download. .

If you like this take time to check out my other designs!