Homebrew PCBs

I seem to be seeing a trend here, that regardless of the techniques
used, with care one can get to 6/6 rules.  How do we get past that?
It must be possible in theory, as the big fabs do it.

My laser printer does 1.3 mil "lines" (600dpi) but the quality isn't
good enough to do so reliably (fuzzy edges); I need at least 3-4
pixels across to get good definition with TT.

I think the various elements are:

* Getting a print with crisp edges at fine resolutions.

* Getting that print onto the board as etch resist.

* Consistent etching with little side-etch.

* Thinner copper?

Does anyone get 5/5 or better, reliably, with home etch?  If so, how?

Random thoughts:

Would a 1200 dpi laser printer give better edges, or just smoother
curves?  Is there a paper trick to keeping the toner were it's
supposed to be?

I read one home fabber printed their TT at a 45 degree angle to get
more consistent results.

Photo: Inkjets can do 1440 and sometimes 2880 dpi, what limits those
to 6/6?  Would having the UV source further away from the board result
in better edges?  What about the thickness of the photomask?

What about 1/4 oz copper?  I usually use 1/2 oz, and I haven't seen
1/4 oz in my usual places.

Injets: Anyone try writing a custom print driver that forces all the
colors to be used, overlapping, making a nice thick print?  I've tried
doing that with my color laser, but I haven't found the command to
turn off the "smarter than the user" mode.