I actually found two of those wavy plates at Goodwill and the mug at a yard sale. They were the perfect match for this project! So here's what you'll need:
2. Length of PVC
3. PVC cutter
4. Silicone adhesive
5. PVC coupling with a threaded end
6. PVC plug
First, you'll want to take care of the gluing. Use the silicone to glue the plate and the mug together. Then the PVC plug - well, this needs some backstory! I desperately wanted to put this project together without drilling holes in the bird feeder so I headed to the plumbing section of my local hardware store. I searched high and low for a cap that I could put on top of the PVC pole with a flat surface for gluing to the bottom of the plate. Unfortunately, every cap in the plumbing isle had a curved surface, not ideal for attaching to the plate. So I grab a plug that would screw into a coupling. It sort of has a flat surface but there is a giant crevice in the plug.
This method also makes for easy cleaning. You can just pull it off the pole and bring the feeder portion to the sink.
If you figure out a better solution for the plug, please do post it below! Enjoy!