Project: Camera intervalometer

I've decided to embark on my first circuit design project. Going to try to build myself an intervalometer that I can use with my camera.

My plan is to take what I've learned (and will learn) about 555 timers and try to build a circuit that will generate pulses at variable intervals. The pulses will (somehow) short a connection to ground, triggering the camera shutter with each pulse.

Sure, I could do this the easy way and go with one of the many designs posted at places such as Instructables, but coming up with it myself will be much more educational.