Not A 3D Printer
Mac OS Graphics & Design
Why spend $3000 on a 3D printer, when you can have way more fun, and get the same results with some cardboard, glue and a little patience?
Load up a 3D model (obj, dae or stl) that you've made or grab one from a site like thingverse.com. Enter the thickness of your cardboard, and how big you want your object to be, then print out the plans to make your own REAL object. Once printed, glue each sheet to some cardboard, cut out shape, and glue your layers together to see your virtual object become real.
Like a real 3D printer, some models will produce better results than others, so experiment to see what works best. The only limit on size is the paper of your 2D printer, so try orienting your object to give large layers which fill the page without needing so many layers. For really large objects you could use styrene tiles or add spacers between the layers. You could try using some kind of filler, or smooth our the layers once they're printed.
Let us know how you get on - we can probably sort out any problems if you email me (firstname.lastname@example.org). Even better send pictures of your finished models - we'd love to see what you make!