Even with having to register,
www.3DContentCentral.com is a great resource. You will not only use it in FIRST but also if you go on to become a professional designer. If you have non SolidWorks format files, then I would use STEP. Most likely the components you will download are purchased components and you will not modify them. You want these components to be as lightweight as possible. Add reference axis or plane if you need to (Insert, Reference Geometry, Plane). Concentrate on your value added to the design, the parts you have to machine - you are now down to 5 weeks. Marie