3D printing folks, tell me about 3D modeling of parts

This is very coincidental, as I am receiving my first 3D printer today! So far I've been digging into Tinkercad, Fusion 360 and Blender. Seems like Tinkercad is great to learn the basics on, but feels limited quickly. I'm installing Fusion 360 now and will probably try Blender if I decide to go more toward artistic/model/figure-type stuff
 
I've been printing for a while, but I didn't really get into modeling until my day job ran out of things for me to work on and paid for me to take SolidWorks classes. I never finished my certification, I'm not an expert, but I got pretty comfortable and now I can design most of the things I would reasonably want to print.

A couple tips for those beginning the adventure of 3D modeling:
  • Every 3D drawing starts as a 2D drawing. You'll start with a "sketch" that you will then extrude into the 3rd dimension. Once you have your first 3D shape you'll add more 2D sketches to the surface of it that you will either extrude or cut, and that's how features are added.
  • Get comfortable with your software. There are a few common commands you'll be using over and over; figure out what they are and where they are in the program, and learn keyboard shortcuts (where possible).
  • Watch videos! With the increasing popularity of 3D printing, there are countless 3D modeling instruction videos being added constantly. I would recommend picking a "series" where one person does multiple videos to teach related concepts, that's typically how professional or academic courses are taught.
One thing that's a little trickier, you'll need to start thinking about designing for manufacturing. It's possible to design something that's very difficult to print well, but there are things that can be done in the design to cater specifically to 3D printing. Things like slope angles, overhangs, corner filets, etc. are things you may not be thinking about when you think about what you want something to look like, but they become important when you slice it up to print it.

Hopefully some piece of that is helpful, again I'm not an expert, but I have enough experience to answer some questions.
 
SolidWorks and Rhino are the old “professional” standards, and even if you are a quick study, can be slow to learn. (Plus SW is stupidly expensive.) Starting on a web based, free platform makes a lot of sense; while programs tend to use different approaches, you still begin to get a feel for how shapes get made.

Things may have improved vastly during the past 5 years (since I was doing hours of this a day), but back then, working with a scan could take more work than starting from scratch. A lot depends on what your printing platform is; extruders are much more tolerant than SLA or polyjet, for example. There are online “repair” sites, that sometimes work automatically.

@vigilante398, above, makes a very important point. (Actually, he made many!) But I’m interested in one of them, because I’m sick of seeing failed parts due to this—filets! Internal cutouts where straight lines meet—whether you’re printing, laser cutting, or machining, are inherently weak, and prone to having a crack develop (and rapidly travel) right at that corner. Put a radius there. Even .020 (0.5mm) radius is fine, and visually, it’s still a sharp looking corner.
 
SolidWorks and Rhino are the old “professional” standards, and even if you are a quick study, can be slow to learn. (Plus SW is stupidly expensive.) Starting on a web based, free platform makes a lot of sense; while programs tend to use different approaches, you still begin to get a feel for how shapes get made.
I love SolidWorks because it's what I know, but I really don't recommend it to anyone unless someone else is paying for it for you. Everything I personally do in SolidWorks could be done just as well in Fusion360. Also my brother-in-law (a mechanical engineer) recently introduced me to Onshape, a free web-based CAD tool that he's started using since he changed jobs and no longer has access to SolidWorks. I haven't done much with it, but it seems to be every bit as capable as something like Fusion360, and it's free to sign up, plus you get cloud storage for your design files so you can work on them anywhere you have an internet connection.

@vigilante398, above, makes a very important point. (Actually, he made many!) But I’m interested in one of them, because I’m sick of seeing failed parts due to this—filets! Internal cutouts where straight lines meet—whether you’re printing, laser cutting, or machining, are inherently weak, and prone to having a crack develop (and rapidly travel) right at that corner. Put a radius there. Even .020 (0.5mm) radius is fine, and visually, it’s still a sharp looking corner.
Yup, all the early things I designed ended up eventually breaking because of all the sharp corners, I had to learn that one the hard way. This brings up another good point though, in FDM printing you're doing multiple flat layers on top of each other, so the direction of the layer lines in relation to expected stress on the part is something to keep in mind when you're slicing your part for printing. I've had parts that I printed at a weird angle because they ended up being stronger that way.

So now you have a learning curve when designing, a learning curve when slicing (setting up your file for printing), and a learning curve running the machine itself :P It's a lot of fun though, and it's a neat feeling to hold something in your hands that previously existed only as an idea in your head.
 
I dont draw much stuff for printing other than something practical here and there... I have 3 printers in total running all the time here because 2 of my kids are big into halo cosplay
 
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