Bottlebrush wood is another good wood that is great for gnawing without potentially damaging birds beaks because it is not as hard of a wood like Manzanita. It's a nice barky wood with great texture and not slippery like Manzanita and Java wood. If you start with a nice thick piece as the trunk on a rolling base with good rubber casters, then add as many extra branches as you want with double wood SS hanger bolts so that the extra branches can be replaced individually whenever they get destroyed.