If the images they show in the video are of the final revision of the device (unlikely), it should not be difficult to make a close copy of it right now.
EDIT: Mocked it up as best as I could with made-up numbers for diameter (~3.1") and taper angle (2.0deg) since I am to lazy to go out to my shed and get my electric leaf blower. At 0:55 in the video there is a close-up of the end of one of the mufflers, and it looks like it is made of multiple pieces, with some black material lining the outer shell. I am going to guess that might be something acoustically absorbent, but inexpensive and easy to get, like a sheet of neoprene with an adhesive back. That way, you can stick it inside of the outer shell and then insert the center with the helix. That is the kind of material I would expect in a senior design project when you are iterating through designs and need stuff cheap and quick.
So, I designed it that way for the one I did. https://imgur.com/a/Qr0vOhb
I'll probably get my leaf blower and update the model so it fits on my leaf blower, and if it works well, I'll post it to Printables and Thingiverse.