I'm thinking about investing some time in designing a small (~800x600) router to cut upto and including aluminium. My existing work area supports a bench-top design, sat on a DIY pine workbench. But, is there a genuine advantage in knocking up a free-standing steel frame for this. Would a steel frame, say 100x50x3 box (it's a good price, and the online deflection calculators suggest it's a good geometry) offer advantage over a floating bed made from the same, sat on top of a bench top.

I do have a tig welder that's collecting dust.

Sorry - my background is in the soft-skills of sparks and computers, I don't understand this 'ere mechanical stuff.