I made a rotary mobile phone: https://www.stavros.io/posts/irotary-saga/

Also an e-ink display that shows my calendar (and home power usage):

https://www.stavros.io/posts/making-the-timeframe/

Also a LED stick that lets you add images to photos in the real world:

https://www.stavros.io/posts/behold-ledonardo/

And a toy bus that shows you when the next real bus is coming:

https://www.stavros.io/posts/bus-stop-bus/

A 3D-printer-etched PCB: https://www.stavros.io/posts/make-pcbs-at-home/