I have one. All I used was a safety pin, and paint. No, not a good idea, but nothing happened. So, I've got a tattoo, but it's fading and will probably we gone by the next year. I don't suggest it. But, no it'd not hard. It just takes three hours of poking.
DIY tattoos can be safe, and difficult, but also can not be if you don't know what you are doing. Granted, you've got to take the leap somewhere, but make sure you get the right equipment and read up on it before you try it. I personally haven't tried any myself, but I have helped set up and prepare for both tattoo guns and hand poked tattoos. It's very painful to tattoo yourself with either method, and tends to be stressful. They also tend not to turn out the way you wanted (for instance, my SO has a crooked-ass star on his leg that he hand poked for the first time, as well as a bolloxed up wedding band that he tattooed with a machine), and take a lot longer.
my first tattoo was done DIY. it's on the back of my left hand. we were all hanging out at steak and shake. and we found out that our waiter was just outta prison and he told my friend how to make a tattoo gun. he used a playstation 2 rumble pack a mechanical pencil some guitar string a nine volt battery some wires and a needle. (he pimped it out later with a pedal and some shit but that's not how i got mine done) and then yeah we used india ink. it's been seven years since then and it still looks like it did day one. which i should point out means that it looks obviously homemade. this will not give you a shop quality tattoo. but it's cheap and fun!