As you can see above, there are a ton of different 3D designs out there that people have had tattooed on their body. You could easily print off one of these pictures and take it to your tattoo artist of choice and have them give you the same tattoo. However, you should try to do something that is more unique to you. Therefore, consider adding some text near the tattoo or even have your tattoo artist make some alterations to the design that you want. That way, your tattoo will be completely unique and no one else will have a tattoo like you.
Talk with your tattoo artist and see what they can do for you. Certain tattoo styles look better on certain body types. Therefore, if you pick out a tattoo that may not suit you, your tattoo artist will inform you of this and will suggest some adjustments to the piece. That way, your tattoo will look as good as possible.