readily machineable heavy metals names we used, like everything else, change over time based upon local availability.
once upon a time it was Mallory, like around the mid nineteen seventies,
then it was CMW-1000, like in the early nineteen nineties,
now it appears to be NAECOMET HM.
https://naeco.net/tungsten-hm/
I haven't priced any lately but in the past the project application really had to merit the expense, ie be sitting down.
Depleted uranium will require appropriate manufacturing facilities and credentials for >7kg.
https://www.nrc.gov/reading-rm/doc-collections/cfr/part040/full-text.html#part040-0022
If you can readily buy the weights pre made just do so but know what you are buying, metals densitiy chart:
https://www.engineersedge.com/materials/densities_of_metals_and_elements_table_13976.htm
Also please realize adjusting bar end weight for the purpose of efficiently reducing vibration is most effective at a specific frequency, there is no one-fits-all silver bullet. Personal iterations will be necessary.
Vibrations in the hand grips are merely a symptom of the entire system. The S10 is not renowned for it's smoothness. To me it feels like a motorcycle should feel. I like it. But then I also prefer ambient temperature beer, unadulterated whiskey and Italian firearms. It's all relative.
I dare say if I expected the Super Tenere to be a highway armchair I'd be disappointed realizing I'd maybe have selected the wrong motorcycle for the trip. To be fair, a short quick scoot prior to purchase is all we normally experience and, similar to being married, adjustments are occasionally forthcoming.
When I had the bar ends weights off the S10 it did occur to me they were heavier than steel, I didn't weigh them or apply archimedes so no guess at material.
One might be pleasantly surprised at the effectiveness of simple Grip Puppies at providing the perception of vibration reduction.
Gawd I do ramble. Apologies. The fuel tank is full, the bottles now empty, we've had miserable wet weather the last three days and what do we do on rainy days at home? read then bore people! Forgive me.
All the best.