On Sunday, November 17, 2019 at 7:54:33 PM UTC-5, wrote:
On Sun, 17 Nov 2019 22:14:03 +0000, Jake Chominsky
m wrote:

I have an 1950s home with older wiring. Most of the house only has a black
and white wire connecting to lights and recepticals. I want to do a 3-way
switch. Currently, the power is coming in through the light then connecting to
the on/off switch. How could I install a 3-way if I can only add a new wired
line from a new switch (#2) to the current light and also cannot upgrade or
touch the existing wired line from the current switch to the current the
current light? The reason I cannot touch the existing line is because it is
behind 2x4s and walls whered I have to demo a wall which is outside of my
capabilities.

I would look at a wireless solution. There is no way to add a 3 way
loop without running 3 wire plus ground cable.

He only said it would be difficult to run a new cable where the existing
cable run, not between the existing switch and the new proposed location
and he implied that can be done. That's all he needs for it to work.