I've got a Meyer lemon that I espaliered against a south-facing fence. It is not regular in shape. I just kept cutting off the branches that were perpendicular to the plane of the fence. I guess you could call it fan-shaped but it's a pretty irregular fan. I thin it out so that the fruit is all exposed to light and air. Not a lot of work. Bears heavily.

Interesting. About how high, wide, and deep is your tree now? We will need to put up a support structure on the wall, I think... Did you loosely tie the tree branches to guide them up the fence, or did you simply prune the tree as it grew?

Here is a not very good current photo. It's been in the ground for eight years and I mostly just pruned it. I think that I tied a few branches to the fence at first but now it is free-standing. This side of the fence faces south and although it is difficult to discern from the photo, the plant is very flat to the fence. Because it is a lattice fence, the plant was able to poke through the other side and to my surprise is almost as big on that side as on the south side. The north side faces a driveway so I didn't bother to prune it in any way an it has more fruit than the south side!

That is so helpful to see. The tree is doing beautifully in that location!

Yeah it's happy. It's not particularly elegant, as some espalier can be, but my goal was just to keep it so that the fruit was easily accessible. One of the nice things about espaliered fruit trees is that the fruit ripens evenly and is easy to pick.