I generally use mine to test fitment of parts that I'm going to machine. While 3d printing takes a while, hand machinging things on my manual mill takes a LOT l

I generally use mine to test fitment of parts that I'm going to machine. While 3d printing takes a while, hand machinging things on my manual mill takes a LOT longer and the material is more expensive. I made a mount for a motor for a skateboard with an irregular truck shape in about 8 prototypes with the 3d printer. Then I cut the metal part out in one go and it fit perfectly. Also for custom brackets and enclosures they're great. You can make all sort of custom one off parts with a 3d printer and they're good for at LEAST mocking up a prototype if not even making a real working prototype. Even more fun, I've got a project to convert my mill to a CNC, and round one of that is to 3d print the brackets, attach them and then cnc up the actual brackets from aluminum. Then replace them. 3d printers also let you do things like lost plastic casting, lost wax casting, etc. But the fitment and layout thing is not to be ignored. When you're making parts that will go into real machines, it's really hard to get good measurements of the real part. Lets say I'm making a part that goes in a car. I can get lots of measurements by hand but I'll likely be off as it's kind of a free-hand thing. You can then cad up and print the part and then go shove it in there and see where you're off, measure those gaps, alter the cad, reprint... These parts are pretty cheap (generally less than $1 each for materials). Whereas having a dude in a shop cnc up a real one is quite expensive, running $100/hour machine time. The other benefit is you get to test placing your part into the machine. You can often make parts that work but you can't get them in to the machine without say taking THE WHOLE FRONT END OFF OF A CAR, which in itself could take 8 hours of mechanic time. I've also got a bunch of misc things. I've got a flower vase my wife likes in black plastic that I sealed that just looks different. And I've got a bunch of coasters I cnc'd up that are custom that I use and I rally like. I also cnc'd up a custom kindle hard case for my son with his name and email on one side and a silouhette of Optimus on the other side. He loved it. Those things are just general crafting. I've also learned CAD much better because design -> object is very quick so some weekends I'll just doodle in cad and then start the printer and start playing games while it does it's thing. Then again the first 1/2 of my undergrad I was a Mech E, and I worked at a game studio for 3 years so I'm pretty fluent in 3d design compared to the average person. But if you can run around a map in a FPS once or twice you generally have enough 3d spacial awareness to do modelling. Computers make this much easier as you can rotate the object live which connects the dots in your brain that the old multiple view paper form was much harder to do.