Pour casting concrete into rubber gloves, being carefully to remove air bubbles from fingers. Mould into position working fast before concrete sets. When set, peel of rubber gloves revealing your concrete planter.
Log Bird Feeder - 23 DIY Birdfeeders That Will Fill Your Garden With Birds (my note: I haven't looked at all of these, but at least one is a terrible idea. The window birdfeeder -- birds could fly into the glass and hurt themselves.