I think my personal favorite physical thing that I made was a music box that plays of the voyager golden record. I made it as a Christmas present for my girlfriend. It is light actuated so when you open the box it starts playing a track from the record, skipping one track ahead each time it is opened. It mostly uses off the shelf components for the electronics, and found and decorated the box (sanding/staining/varnish on the outside, and a watercolor painting on the inside. It took quite a lot of effort to get the audio formatted and compressed enough to get it all working, but I think it is really a beautiful object on several levels.