For the avocado planting a fresh bone is needed (it is better to have several). We look at the drawings.
And when small plants grow, we plant them in one pot and form a pigtail (preferably between plants put the support - a dense branch).
Under the future thickening of the trunks weave is made freely, with holes. Lateral shoots are removed.
If the plant strongly discards the leaves, then we pinch the tops so that lateral shoots go.
In general, there are several types of weaving trunks: spiral, double spiral, pigtail, grille.