*Pushes up glasses* Ackshuallllllyyyyyy there is no such unit as Saturnine Terminators.
Joking aside...
What's wrong with the Etsy ones? A quick Google search says they're
the same ones done by Tortuga Bay, which I was about to recommend (though you'd have to wait, as they are based in Ukraine...). I believe they have the STL files, but physical models obviously cannot be done by them.
There's also
these ones from Pop Goes the Monkey and
these as well. Failing that, you can convert them. Both
Krautscientist and
myself (plug plug) have done conversions based around using horse barding for the distinctive huge shoulderpads. Finally, there is (was, not sure what happened to either of them, but I suspect I know why...) a
scaled up version of the original Termie minis from Troll Soup minis, now scaled to stand roughly the same scale as modern
40k minis. Apologies for the Spikeybits link, but that seems to be the only place where the images of them still are.