I came up with a plan for machining long pieces of wood. It wouldn't be round so I don't plan to use a lathe for this.
What I did come up with was an idea for a long, long (~72") table and a ballscrew. I'd mount the linear rail's bearing blocks on the fixed platform about a foot apart, with the cutting head always in between. And a long table with the rail mounted on the bottom. Rotary table and tailstock here on top.
Now here's the thing. A LONG linear rail is frequently very expensive, but ones not in a matched pair can be cheap! But is it necessary to have 2 rails? I can make the table stiff so the moving table won't flex or twist. That's not the problem. The question is, how well will one rail itself resist torsion so the work doesn't rock front and back as the whole table and rail rock in the slider? The length of the table is actually irrelevant at that point, it's whether the single linear guide itself resists torsion.
If there's significant slack in that direction, the work's going to chatter and that'll be bad news!
The stock would be 2"x2" wood and about... 4"-5" above the linear rail. That's a critical factor since the torque created depends on the distance from the rail.
So, what's a linear rail like in this regard? I've got a Bosch I'm looking at, found a THK but the price was much higher.