Custom coolant recovery tanks?

I have a crappy old one that works, but I'd like to replace it with something cool as well as functional.
I was thinking one of the aluminum gallon mini beer kegs, but I think it might be too big.
If I could find a half gallon one, that would be great.
We have a tig machine so we can weld nipples and a cap on it.

I have seen hundreds of them here and online, so I have a pretty good idea what is out there and been done as custom or aftermarket.

Like I said, a half gallon keg would be perfect I think but I don't drink so not sure what's out there besides what I generally see in stores.
Been watching thrift stores, swap meets and yard sales as well but not seen what I want yet.

If I can't find exactly what I want I'll just build on out of 3 inch aluminum tube.