<p>In general 3D printers are compact and smaller than RP machines. That's ok. But, what's the difference? 3D printers can be used as RP machine too.</p>

[{'answer_id': 443, 'author': 'Daniel M.', 'author_id': 156, 'author_profile': 'https://3dprinting.stackexchange.com/users/156', 'pm_score': 3, 'selected': True, 'text': "<p>All rapid prototyping means is automatically producing a physical part from a cad model. 3D printing is a way to achieve rapid prototyping. There are 2 main methods of rapid prototyping: additive, and subtractive.</p>\n\n<p>A 3D printer is additive- you add materials to an object layer by layer.</p>\n\n<p>Usually, when people talk about a subtractive machine, they are talking about a CNC mill (or lathe), which tend to be extremely large (most are over one ton). You start with all the material there, and you subtract the material that you don't want. This might be what you are thinking of.</p>\n"}, {'answer_id': 449, 'author': 'Leo Ervin', 'author_id': 381, 'author_profile': 'https://3dprinting.stackexchange.com/users/381', 'pm_score': 0, 'selected': False, 'text': '<p>To add to the above answer, a very simple way to say it is that FMD 3d printer is a rapid prototyping machine which has a component called an extruder which pulls and melts plastic which the machine then lays down.</p>\n'}, {'answer_id': 591, 'author': 'qtron', 'author_id': 597, 'author_profile': 'https://3dprinting.stackexchange.com/users/597', 'pm_score': -1, 'selected': False, 'text': '<p>A sintered metal printer is a version of a 3D printer that is rapid, but expensive. Seen 1 for 800,000$aud\nUses laser to melt metal particles like titanium.</p>\n'}]
['https://3dprinting.stackexchange.com/questions/442', 'https://3dprinting.stackexchange.com', 'https://3dprinting.stackexchange.com/users/334/']