I'm wondering if you shouldn't have different rules for hardware than for software? For instance, what if somebody told him Apple had patented indented buttons and he couldn't use them? I see lots of good improvement ideas here in the comments.

Actually tooling up all these parts will cost him $100,000 before a single person can "try" one - so obviously he needs all the suggestions he can get before that stage.

Or, maybe "Show HN" is just better suited for software?

The rules are slightly different for hardware in that readers aren't going to to be able to immediately try it like software, some essentially unique builds that nobody (statistically) is going to try come by sometimes, etc. A thing that doesn't yet exist can't be showhn, though.

There's nothing stopping anyone from posting about unfinished things, they just can't be 'Show HN'.

We do have different rules for hardware! - that's in the same document: https://news.ycombinator.com/showhn.html. There should still be more than a signup page though.

Thanks @dang! Sorry about the confusion, I had not read the show hn rules in detail.