Putting letters on a rubber bracelet

[hollysaurusrawr.livejournal.com]

My boyfriend and I bought this http://www.craftsetc.com/Store/ShowProduct.aspx?p=134841 kit from Hobby Lobby. However, as we kind of predicted, the kit sucks. We want to use the bracelets as merchandise for his band. Any ideas on how to get letters (we'll just be putting three letters on them) on the bracelets? We'd like it to be something permanent, as opposed to like, adhesive letters or anything.
Thanks!