... sound batting and/or weighting speakers ...

Hello,
I like MilerC’s idea of the bluetac. Many times for computer speakers I have done this or added a cut mouse pad and put it under the speaker to clean up the sound.     You can take a sandwich bag and fill with sand, shot, or copper BB’s and open up the speaker and put the full bag on the Inside bottom of the speaker. You would have to do this through the plate on the back or the driver on the front.     Last you can put a piece of cut foam in the port to make a more sealed enclosure, but I am not a big fan because you are changing the frequency of the speaker and you will lose bass. You can try this by putting a sock in the bass port and see if you like this sound. If you do you can then go get foam and make it look better later. 

I have maggie LRS speakers. Very low mass and lightweight. No box. Ribbon drivers. They don’t vibrate at all so I’m thinking the vibration spoken of here is an inherent feature of dynamic drivers in wooden boxes. My previous speakers were Polk Rtia 5 floorstanders which were heavy ( 50 lbs ea) made of real cherry wood (not crummy MDF) had curved sides, and internal boxes and bracing isolating the drivers from each other and vibrated almost not at all.They had excellent sound quality, but they can’t compete with maggies. When I listen to them now all I hear is a box. Amazing how I never noticed this until I started listening to the maggies.
I had dynamic wooden box speakers for 40 years and never knew I was hearing a box until the box was gone!!! Not sure why maggies don’t vibrate. But the sound quality of them is like nothing I’ve ever heard before. Especially acoustic instruments. With loud distorted electric guitars, not so much. But that distortion is, IMO, an inherent feature of the instrument. The maggies make poor recordings sound awful. The Polks were much more forgiving. Everything sounded good on them.Also they really ROCKED, which the maggies don’t do. But I added a B&W 400 watt powered sub and that really helped out the maggies. They don’t have much response below about 60hz. But the mids and highs are probably the best you can get except for electrostatics which IMO have other drawbacks like they have to be plugged in and present a difficult load for most amps. My amp is a Schiit Vidar which works really good with the maggies. I agree with the others here who said instead of mickey mousing around trying to reduce the vibration you should either forget it and just enjoy the music or get better speakers.

Upgrade to a good speaker.

amg56,
I'm guessing you're in Australia, have you heard Mike Lenehan's ML5's up on the Gold Coast? stereo.net.au forums are full of members reviews of his loudspeakers. I have his ML2 Ultimates with the HD3 and 4mm steel plates lining the enclousure.
I've found high praises on Kyron Audio. I might have go have a listen if I'm down in Crow-eaters territory again.

We don't know the motivation of the OP; whether to band-aid the speakers or dump them to move up. It would help if there was more direction given as to the ultimate goal. 

I found the Lenehan ML1 Bookshelf Speaker I reviewed for Dagogo.com to be a wonderful product, well built, with good sound. Read my review of it at Dagogo.com