Hi Jon,
I'll stick my neck out and offer my thoughts. This one is a bit of a puzzle because the canes resemble those made by a number of makers. In my opinion this is most likely Murano, very few makers use colored glass to encase with and it is a feature most commonly found in works from Murano. The colored glass and the flat polished base make me believe this could be Muranese.
The canes themselves are where the questions arise. From the few whole canes that are visible they are not typical cog style Murano.
Lastly, and this is a stretch, the overall appearance with numerous small bits of partial cane heaped high in the dome reminds me somewhat of a Pairpoint scramble.
Could you upload some images showing canes from the other sides of the weight?
With some certainty I can say that this is modern made in the last 30-40years.
Hope this helps...somewhat.
Eric