I highly doubt you will find an off-the-shelf system.
Absolutely, use of the word system seems pretentious when I 'd be happy with a mini-sledge and anvil except for the noise. 8-)
> get a spare set of dies for your crimper and grind it to get what you need. A Dremel with a cut-off wheel, small carbide burr, and some jeweller's files should do the trick
Yes that will give precisely repeatable results, much better than a hammer.
But I haven't found die sets for sale that fit my AMP 600850 Rota crimper cheap enough to destroy, or at a small enough gauge opening.
I also have MS' CMI version of the AMP 55893-1 "double crimp" for heatshrink terminals https://www.amazon.com/dp/B00HPLHY9C/ref=cm_sw_su_dp
but it's too rounded, maybe start with that then do something else to further flatten one side.
But maybe better to just check out the chinese X-ton wannabe's, look for something in a smaller size and non-hydraulic, and jig up a die for that. cheap but another big tool taking up space.
I also have a Rennsteig 624 000 3 frameset, thousands of dies available for that, but again pricey roll of the die (hah!)
> Using a flat die on a round cable will make it hard to get a sufficient, air-tight crimp.
We are talking about fine **stranded** copper at only AWG 16, so it's not round like a solid wire would be.
And it's surrounded by a small and soft copper torus getting compressed from its "sides" - in reality an oval on its side, squished top to bottom.
Say I found a "penny presser" cheap, and the finished "crimp height" was only half a mm, much thicker than a single strand, in this case 30 gauge or a quarter mm. Guaranteed cold-welded, gas-tight junction, right? But way over-compressed - even if even increased resistance / lower conductivity is not an issue (due to increased surface conract area), the junction will be mechanically weakened more than necessary.
So with "just enough" (much lower) compressive force, I reckon at a crimp height somewhere between 1.5 and 2mm in this case, the strands will be well deformed but not too much, each no longer round in cross-section, but squished up next to each other like a honeycomb, just enough for that cold-welded, gas-tight required result.
I'd love to slice the resulting "coin" open to get a cross-section micro-photo, but if not, pull tests will be enough proof.
For those new to crimping: