Rapid Resizer can extrude SVG designs into 3D STL files for 3D printing.

You can upload an SVG on the New Project page. Or you can make a design using the Letter Stencil Maker or the Designer.

From the resizing step, click Customize then 3D Print.

In the extruder step, you can size your design then download an STL file. You can print that file on your 3D printer or send it to 3D printing service such as Shapeways.

Here's a (not affiliate) link the 3D printer, pictured above, that I use.