If you are bored of standard t-shirt designs, you can make some modification on your t-shirt. It is up to your imagination and creativity to apply any kind of modifications to your t-shirt or maybe other clothes if you like. In order to try a such modification work, you should make sure that your planned change would work.
Rather than going on your own, it will be better to watch some related diy tutorials to see whether your modification plan would work or not. After understanding the process, you can start applying your modifications.