I did a button matrix using galvanized wires (only one thread, 1 mm thickness) and it works. (But) I don't know, it's a good material o it can melt with temperature? Maybe galvanized metal is a "bad conductor" of electricity, I read about it but nobody explains the reason.
I'm not planning to use it on the outside, it will not move from home :)
It's a little project that will work with batteries, at 5/10 V and 0.5/1A at maximum.
Thanks in advance for your time, and regards!
Edited: The wire I'm talking about is this It's something like it: https://www.amazon.com/50143-Gauge-Galvanized-Steel-Wire/dp/B001EX57ZK/ref=sr_1_3?ie=UTF8&qid=1524132120&sr=8-3&keywords=galvanized+wire
there are "versions" made from aluminum, iron or steel. Aluminum seems the best in terms of conductivity, copper is better but it gets "oxidation" easily.