Without a doubt, Thomas is a well known disciple. There is plenty of information available for the pillar project. But be aware that “doubting Thomas” is a wide-spread expression and you will have to wade through it if you do your own internet search. To make it more accurate, search “Thomas in the New Testament.”
Start here gathering information about Thomas.
Wikipedia offers some material on Thomas.
Some themes can be found at this site.
About.com Christianity page talks about Thomas.
A YouTube video for kids about Thomas.
What can we learn from Thomas?