Shive wave machine (very poorly working)

This is an attempt to design a 3D printable Shive wave machine, which can demonstrate all kinds of wave behaviors including reflection, impedance matching, standing wave etc.
The stuff I managed to do is more like a 1D coupled harmonic oscillators. It is not traveling well. I need a larger printer.

• The first version is meant to be hang. The two polarizations are not very separate and easily excited at the same time
• The next two versions can stand up, and they have different stiffness and thus different frequencies

See more at: https://sciencedemonstrations.fas.harvard.edu/presentations/shive-wave-machine
A video from Bell Lab and John Northrop Shive: https://www.youtube.com/watch?v=DovunOxlY1k&ab_channel=AT%26TTechChannel
There are company selling it: Complete Wave Motion Demonstrator: https://www.pasco.com/products/lab-apparatus/waves-and-sound/ripple-tank-and-standing-waves/complete-wave-motion-demonstrator