honestly, just in terms of fairness i wouldn't use these dice, i would rather have a flat surface with a sharpie on number just so there is the most equal chance a number would land, opposed to once side having less material making it lighter so a 1 is a number that statistically comes up less. the other reason is dice like that can be very cheap, i think something like 10-20$ for a few hundred.
as for machined... i'm not sure, i know there are metal dice, just googled it, fully machined dice are all ridiculously expensive it seams.
wait, just looked at it some more, apparently the stone dice i like are also cnc machined, amethyst, jade, sandstone... these ones top out at around 70$ most being around 40...
now i'm interested to see what the cheapest machined die set is.