'Hardware'

Thinking about the low-tech ways to make and contribute colour grids, I've considered a few options:
things in the box:
a pad in the cache, seperate to the logbook
a combined logbook and grid making booklet
waterproof notebooks
things to take away and send in:
postcards to make a grid and post in (downside: need a PO address, extra costs and handling challenges)


Sound:
all sorts of interesting sound devices could go in the box, but cost adds up, battery life/replacements and whether people would try to take them away are all issues to consider...

http://www.talkingproducts.co.uk
I like these sound labels, designed for medicines, but adaptable for other uses, with 20 second recording. However talking badges also look quite good - particularly as they can't be re-recorded and can have images attached.
They even do a talking treasure hunt set!

or just the recording set and button to fix into something myself and more here.
Crazy sound (and LED) active items from bottle openers to pens...
...or there are ready made birdsong stickers (as a way to learn the calls of different species..)