I have not used the colander method for trunk thickening purposes, but have had great success in the recent past with both a crabapple and an apricot in rapid development of strong root mass. I acquired both in early spring, and put both into a mix that was 80% akadama and 20% pumice, and used spaghetti-strainer sized colanders from the dollar store. By September I had nice big root mats. I then gently slip-potted them into grow pots, not working the roots at all, just plopping them in with a layer of akadama underneath and about a finger’s width of new soil all around. This was summer before last. Last summer I had excellent vegetative growth including sacrifice branches, and both trees are thriving this year. This method requires much more frequent watering, but the aeration does something magical for root development.. I’m not at all certain that either tree would have survived going direct to grow pots, given the feeble roots they started with.