I really like the look of old wooden letterpress type, and have picked up a few here and there at flea markets and the like, mostly for decorative purposes. But the great thing about them is that you can use them to make things as well, even if you don't have a press.
I wanted to spruce up this t-shirt so I laid it out on the floor with a few pieces of paper in between, just in case ink seeped through (it didn't), and played around with the arrangement of the letters until I arrived at one that I liked.
I applied some ink to the back with a foam brush (I used Jacquard textile paint but you could use any screenprinting ink). You don't really need too much, just a thin layer. Also don't mind the weird glare on the 5.
And then I pressed them into the fabric by hand, one at a time. I like the varying degrees of texture, how some came out lighter than others.
Finally, after it dried I ironed on the back of the print for about 30 seconds to heat set it. And that's it. The bulk of the project probably took about 5 minutes.