Inventing is about creativity. You must create excessively and push through the monotony and heartbreak of repetitively creating, being wrong, and having failures. You could spend a year designing, doing calculations, drawings and more. Have it prototyped and it not work. If you do not get into the trenches and prototype your invention yourself, your path to success will be delayed and will cost you much time and money. Always try to invent something you can build yourself.
Buy a 3d Printer, they are very affordable now and easy to use. You will have limitations if you are trying to create something large. I tend to shy away from inventing larger objects because of many reasons. Being more difficult and expensive to prototype, cost for shipping, shelf space, and the list goes on.
Look online and read reviews, and you can find a good 3D printer for around 200 Dollars.. This will be your Excalibur Sword during your inventing process. You can literally turn an Idea into a physical object within a matter of hours and test it. If it does not work, you can trouble-shoot why, make changes, print again, test and repeat. Continue this process until something beautiful and functional is born.
I will have an idea pop into my head and I will design the idea in my CAD Program, and have it printing in a hour. There are a lot of top CAD programs, and some are free.. You can find many resources on YouTube on how to 3D print and what programs to use for free. But once you have your 3D printer, you are on the road to being a better and more efficient Inventor.
There have been times that I have printed over 50 different variances of 1 prototype. During this development process I would have discovered something that no one would have ever expected. It could be a breakthrough that no planning, drawing, or forward thinking could have ever created. The more you create, the more you learn, the better you invent.