Given current lumber prices, you may have to hunt down galvanized studs for the surround in the garage.
You need channel for the top & bottom "plates." You'll need a mice big box of 5/16" self-frill self-tapping screws (known as "points" in the trade).
Upside to metal is that you can cut them to fit with tin snips. No having to take a measurement, get off the stepstool, go to the saw, and chopsaw the one stud at a time. Instead, you take the measurement, then put the tape on the stud, then tin snip it to correct length. Then, spin on a couple of points while you are right there (leave the foot loose). Move 16" further down (or 19.2" the black diamond distance on the tape) and repeat.
Invest in some mineral wool insulation and you get a two-hour wall assembly for your safe surround.
I have this habit for such builds to lay in a hank of 12/2 romex at 12" up, then some 12/3 up around 72" off the floor, and just leave the ends looped in the existing walls. Just never know what sort of new power or lights that might want installing 20 or 25 years down the line, and having the material in place can help.
That's my 2¢, spend it as you will.