You have absolutely posted in the right place, Everything Else would have been fine too - but the likelihood that someone will answer will non PG settings is high, so this is a great spot.
That being said - yes you can mark some metals, but actual etching (digging a hole into metals) is beyond the capability of a 40W C02 laser. So, presuming you’re talking marking - let’s get you moving.
@dklgood’s link is definitely helpful for what not to laser (Copper = BAD)
Folks have had luck with plain water on steel, as well as mustard & vinegar!
You definitely have some testing in your future, but doing a search for the metals you’ve found (tin & aluminum (and aluminium) will get you started.
Also, consider if you paint your surface you can then either etch away the design, or the area around the design to give yourself nice contrasting look.
Lots of reading ahead for you - and we look forward to your results!!