This is a sweet tutorial on how to forge a fingerprint with simple elmers glue and some time, well alot of time:
In order to fake a fingerprint, one needs an original first. Latent fingerprints are nothing but fat and sweat on touched items. Thus to retrieve someone elses fingerprint (in this case the fingerprint you want to forge) one should rely on well tested forensic research methods. Which is what’s to be explained here.
The rest has pretty pictures and lots of intructions so click on the original link to get the whole story.
Now, find a practical use for this and post it in the comments.