By Oliver Fry

A plant pot is filled with concrete, in which is placed a vertical plastic pipe to hold the base of a tree branch (branches can be replaced periodically, and can be wedged into the tube with smaller twigs).  This is placed in a large wooden box lined with newspaper to catch mess and make it look less offensive.  The branches can be as large or small as space permits, and need not take up too much room – parrots enjoy climbing and sitting on tall vertical branches as well as ones with thin horizontal and diagonal offshoots. Always wash any branches you may have acquired to remove any traces of insectacides, unless you know they have not been sprayed.
 
Photo courtesy of Oliver Fry

For suggestions of suitable wood for natural perches see http://www.parrotmag.com/parrots-blog/943-natural-perching-is-best