3D desktop printers are really making progress. My sense is that soon this will be absolutely essential for my hobby (model railroading).
Update: You don't have to own one, a number of companies emerging that will print your designs for you. About 5 seconds after I posted the hypothesis that I would soon need a 3D printer for model railroading, I read a model railroad blog post about ordering a custom locomotive shell from this site. From that site saw an idea I had not thought of - custom Legos! How often in my young Lego-obsessed days did I long for a special piece of a certain shape that did not exist. Now, make your own!