SketchUp has a massive library of over 2 million free user-created models to get you started in what they call the 3D Warehouse. You don’t have to re-invent the wheel… you can just download it! Need to add a garage door to your plans? It’s in there. How about a workbench? That’s in there, too, available to drag-n-drop right into your design. In fact, many of the items you’ll find you want to add to your own plan can be turned into plans themselves—like a homemade workbench.
A garage remodel is usually much cheaper than a home renovation because the foundation, roof, and walls are already built. Many garages also have electrical and plumbing installed to some extent. The actual cost of a garage remodeling project, however, depends on what the renovated space will be used for. While a new home gym won't require much in the way of amenities, converting a garage to an office, apartment, or bedroom requires adding significantly more creature comforts.