This model is fully operable once assembled; you can pull out the pin (many times in and out), and the handle springs up. Should fit on most eggs (especially the Easter ones), a 3D-printed egg is optional.

For assembly, you need:
Pen spring
Key ring

1. Put in the spring.
2. Push the handle on from the top.
3. Insert a keyring into the pin.
3. enjoy

It's also surprisingly sturdy; I have been throwing it around and it still holds together.