I don't own one of these Hobo Nickles, but I would like to get my hands on one. The attached website has an amazing gallery of these things. The ones on the site are all made from Buffalo Nickels, but other types of coins have been used. Nickels appear to be the easiest to sculpt.
This is a modern carved 'hobo nickel' made from a 1937 Buffalo nickel by Howard Thomas. This one is a skull and raven he calls “Only This and Nothing More”. There are several pictures of this one at different angles to show the depth of the carving. It is signed on the back by Howard.