Grafted Tree Lattice is easy to make by planting trees crossed at a diagonal and weaving the branches and the trees together. The point at which the branches or the trees cross needs fastening until the graft has "taken" and is strong.
When working with Lattice Trees I sometimes take a branch and sharpen it like a chisel and gently insert it in under the bark where I want the graft. This is best done in the spring when the growth is vigorous.
Willows are often used to make a fence or screen. (Not so effective penning animals, they will eat the bark off). This type of lattice is quite useful along pathways or promenades. Very large walls can be established in this way by planting 20 to 30 foot tall, large diameter trees in a row at apposing angles and weaving branches and the trees themselves in this same way.
I recently created an art piece at a National Historic site in Western Massachusetts. I cut green willow and drove the sharpened ends into the ground in the early spring and they took root. They form two intersecting walls of Lattice Trees. During the summer the grounds maintenance crew, with no ill intention and not knowing any better, came along and girdled the bark at the base of each tree with a grass trimmer and killed them all.