Tuning/Toning a wood xylophone?

Help!! I am taking High School Physical Science, and my table group has been assigned to make a musical instrument. We have decided to create a xylophone. What scale should we use and how do we tone the keys. I understand how to find the nodes but, from what I understand, i have to gouge out the middle of the key (I do not know how to do that). Please enlighten me

Thanks for your time,
Kevin Burito