Thought I would throw this out there too. It might give you some ideas if you build one, or give you an idea of what to look for. I got this used from a shop teacher who needed more wood than an outboard rest. It is heavy enough that I cannot lift it, only slide it around the shop. The school had 3 Powermatic 4224 lathes and each one had an out board rest that had not been used in the two years since they got them. I used it on my older powermatic 90 to turn outboard (and backwards as no reverse or slow speed) Only used it for a large clockface turned from a slice of maple tree. Here's some cell phone photos of the rest, lathe, and the clock. You can see my Stubby in the background (tail stock on the floor) of shot 1. The powermatic is currently set up as a 12" sanding disk, but I have kept it so far because it does longer table legs than the Stubby. And the 3rd photo is the clock. Dots are purple heart. Clock is about 16" across at widest point. I did it several years ago and it seemed a lot bigger then.
Ken Easley