Elf house on a tree! That would be cute in the garden, especially in the tree over grown with ivy. How about some battery tea lights in the windows during outdoor parties. I hear the fairies/elves whispering "home school project" in my ear.
Tuffits: Concrete stepping stones which look like pillows! Concrete stepping stones that look like vintage pillows. Get old pillows, lather with petroleum jelly, cover with plaster of paris. once hardened, remove pillow and fill mold with concrete!
Hanging Jars Spoon Hangers: A fun DIY project this summer was to put glass jars to good reuse and hang them from old spoons that were formed into hooks screwed into the interior wall of our front porch. They really stand out as you enter.
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.