Hollow sections work well if designed correctly. The original FADAL's were mostly weldments, and performed well.

If you've not seen them yet, check out the David Decaussin (one of the original FADAL owners) videos on youtube showcasing his small mill and lathe, as he mentions a bit about it. His channel is at https://www.youtube.com/user/DAVIDDECAUSSIN

And having just searched for that, I've just noticed he has some newer videos which I'm now off to watch!