any interest in a space habitat design app?

You seem to be describing a sort of "Space Habitat Tycoon" game,
similar to the "Railroad Tycoon" and "Roller Coaster Tycoon" games
which have been very popular. Looks like you could be on to
something. The CAD version is something RCT lacks, unless you
download unofficial "trainers," and even then it isn't exactly what
you are talking about.

--- In spacesettlers, joe wrote:

> 1. Who here would be sufficiently interested in such an app to cough
> up, say, $30 for it?

I would. Keep in mind that I am not a wealthy man, and don't remember
the last time I spent $30 on a single piece of software (not counting
when I bought the computer $$$). But I'd scrape together three
Alexander Hamiltons for this.

> Or, does anyone want to be the producer (i.e. hire me to write it,
> and then reap the rewards)?

Would that I could.

> 2. Does anyone have connections to an appropriate publisher (e.g.
> Imaginova)?

Would that I did.

> 3. Any other ideas for how to make this better, or how to make a
> decent business proposition out of it?

You need to either include or make available as an add-on, a mapping
program. As for the rest, well...

In another post on this same subject, you write:

> But in any case, actually modeling the mining and refining of
> materials is beyond the scope of this app.

Yes. It would be a bit much for the player, as well.

But now think about this. You could have a whole series of modeling
programs/games here:
Moon Miner's Challenge
Bulk Transit: Cislunar
Space Hotel: The Game

and of course
Space Habitat: Make It Work (or whatever you decide to call it)

Wow. Yes, my answer to Question #2 is "Would that I could."