I've used a number of different CAD apps, but have to say that anything by Ashlar is probably my favorite.
Of course there is always the old saying: "What's the best CAD program in the world? ..... the one you're most familiar with!".
I enjoy making small parts, I admit. I have yet to really push the limits on size -- I think
I might be able to go to 200 DP on gears, but may have to have the moon in the right position before I can pull that off! The small gear above (first two photos) was cut using 70 micron wire (.0028"). That's already 30% smaller than my machine is rated for, but with a bit of tweaking I've had some pretty good success with that size wire. I've actually run 50 micron wire in my machine before, but it will take more work to get that to run reliably. The tension and power settings get so low with wire that small that everything has to be "babied" to pull it off.
Here's another small part I made (I think I made about 25 of these). Looks simple... but this customer required every dimension to be ±.0001". I had the material centerless ground to ±.000050", then sliced off the "discs" in the wire machine. Then wire cut a fixture right in place and never moved anything -- inserted the blanks and cut them.
But I have to say that some of the model engines I've seen on this site make anything like this look trivial. There are some phenomenally
talented people here, and I'm really enjoying going through some of the posts and reading about what's been built.