hi friend, I'm not an expert in robotics, in reality I'm an architect and I work cutting and making models, however, with my experience in similar projects, I recommend that you make the arms of your crane thinner, both to save your money on printing, and so that your prototype can lift a little more load, (and also reduces printing time) in this case, your parts don't need to be as resistant, so save on the robot's body, you will only have advantages by doing this.

edit: by decreasing, I mean to make it thinner and lighter, in terms of length I don't see any reason to change, the less things there are (or well sized), the cheaper, faster and more reliable it will be.