My local library has one available for use. Being public access they restrict the size of the model to printing in 1 hour or less. The material fee is about $5. Even these restrictions allow a lot of things to be printed for our use. Unfortunately, I've been waiting for the machine to come back from the repair shop, it's been out of service for a month now. One of the biggest roadblocks to 3D printing is not the machine but the access, knowledge & skill to create the model in a decent 3D CAD program. When the 3D model is converted to the print model it is actually printed as a hollow model with a honeycomb internal structure for support. You can specify the wall thickness as well as the percentage (density) of the internal structure. It prints faster, saves material and is surprisingly lightweight.
I designed a cowling for a small twin electric powered scale model that I want to print. To view the sample 3D model, open the attached file in Adobe Reader X or above, click on the image to activate the 3D view and drag the image to rotate in 3D. Once I get it printed I'll let you know what kind of dimensional tolerance it prints at.
Paul