A garden bedder that my dad and I made a few years ago out of some scrap lumber.
It makes beds that are about 30″ wide, which works well for things like lettuce, kale, or other greens. It’s also nice when we want to have double rows for things like okra or peppers.
It basically does the same thing as those commercial bedders, except that it obviously doesn’t lay out drip tape or plastic mulch. But I’m sure the more inventive out there could engineer something up that would do those things and more.
A couple improvements I would suggest (besides making it out of metal) would be to add a wire rake on the back to smooth out the beds, otherwise soil piles up on the edges and slopes down toward the middle.