If you expose B&W photographic paper for let's say 6 months in a pinhole camera (recording sun trails), you DON'T develop or fix the paper. This will destroy the image. Just keep the paper negative in a dark box, only get it out shortly to scan it once and put it back in the dark. It will keep for quite some time.
Here is a nice instruction video: http://youtu.be/wtZOWEB_wcI
I'm guessing this will work the same with colour photographic paper (never tried it myself).
Making contact prints (with daylight or an enlarger) is an other thing.