I bought these off ebay and am so happy with them. It's basically custom letter stamps. Amazon sells a Martha Stewart version but it didn't get that great of reviews. The one I purchased is a WT Rogers Printing kit like this one on etsy.
The letters are clear and easy to remove from each other. The kit was barely used also! Such a great find on ebay. I cant't wait to get started on my crafts. The possibilities are endless for this!