DT wrote:

-snip-

Forms for what? Sidewalks? Stairs? Basement walls? Garden planters?
Plus, we do a fair amount of concrete work and I have never seen an
aluminum form, just steel or wood.

You must be a youngster. I avoid concrete work whenever possible and
I've seen loads of aluminum forms.

And it isn't old technology as far as I can tell. I googled
aluminum concrete forms
[actually as soon as I completed 'concrete' Google suggested 'forms']

Loads of manufacturers out there.

Jim