Re: What 3 liquids can I use to make a liquid wire?

This presents a very interesting engineering challenge.  If the class were
in session now  I’d be tempted to pose it to my engineering design
students.  I can’t think of any set of three fluids that meet all your
criteria.  You might want to consider a gel for one of  the layers, if not
all three.  Some of the gels used for electrophoresis should be clear
enough and are fairly conductive.  You should be able to find more
information from a biological supplier like Carolina Biological Supply. The
gel may also give you a support for wires so that bulbs, motors, and such
don’t drift about.  Whether you use a gel or not there is another issue,
corrosion.  You might mitigate this some with gold or platinum contacts but
that gets us away from being cheap.  Even at the 1 or 2 Volts you’d be
using across the terminals of the bulb over the one month you mention there
would almost certainly be some production of various oxides and hydroxides
if not other salts.  Some of these will be colored and or opaque and could
visually contaminate the area around the wires at the interface between
layers.  Whether not this detracts or not would be up to the artist.  The
production of gas bubbles could also interfere with the connection to the
conductive layers.  There will also likely be the issue that since none of
these conductive gels or liquids is as conductive as wire then depending on
how far the connection of you power source to the conductive layers is from
the connection of the bulb to those layers you may need to provide well in
excess of the bulbs required operating voltage to get enough current flow
to light it.  (If you don’t mind the different look you may find LED bulbs
are easier to light as they use about one tenth the current of an
incandescent bulb.) Just how much more voltage might me needed would
probably be a matter or trial and error.  As a safety note working with
conductive fluids and wet hands can get you a pretty severe (possibly even
fatal) shock even with a 6 or 12 Volt car battery.  Use your rubber gloves
and disconnect power sources. This sounds like fun but do be careful.