ShiftRC
Simple cheap DIY RC receiver/handler.
..., and some more complex. a similar thing can be said for the controllers, I will soon upload the schematics and designs for a steampunk style controller. but for a more simple understanding a simple remote might be a transmitter(led, speaker, or antenna for example) a button, and a capacitor to stabilize the button because every pulse you send changes the state. however high precission control is possible.
Use the project and schematics however you want it as long as it does NOT restrict others.