Here is some more info and a couple more pictures for those interested.
I build them around 5 feet high(don't want them taller than me
). I buy the round large dowel, I think it's 2 inches in diameter and an assortment of smaller dowels suitable for perches. Drill holes the same size as you perch dowels and glue them in using non toxic wood glue. Make sure your perches aren't longer than the base is wide to avoid messes. You can also drill small holes to add food/water/toy cups like this. Sorry but Maya was not ready for this picture.
Cut the main post to size and affix it to the base with angle brackets and small wood screws. For a base I use a wood with a veneer surface for easy clean up. I also add a trim to keep messes contained. A bead of caulk keeps seeds and stuff from getting caught between the base and trim. Your base can be any size you like just make sure perches don't overhang the base to avoid poop on the floor.
Add screw in eye hole hooks to attach toys and other goodies.
Hope that helps. Now get out your saws and screwdrivers and get building.