The first two are my Pringles Snake Eye rocket. Two Pringles Cans, a BT-60 and a BT-50. Everything else is 3D printed. I designed this in Tinkercad, printed it, assembled it, and flew it. To me it's scratch built. But if someone else followed my plans on Tinkercad, I guess it'd be a kit to them. Personally, I think what makes a 3D rocket a "Scratch Build" is the DESIGNING it part. If you're printing someone else's design, that's a kit.
The last little rocket is the Fallout rocket (from New Vegas, I think). Someone else designed the rocket as a 3D print model. I took their design, uploaded it into Tinkercad, and made it a flying rocket with an 18mm core. Even though I did a little modification work, I'd personally call this a kit as the major DESIGN work was done by someone else.
Oh, and I did design one set of parts specifically to be put into "kits" so that we could have a build day with relatives. Though I designed all those, what everyone built that day was (to them anyway) definitely a kit.
I'd be interested in knowing how many people who actually DESIGN and PRINT their own 3D parts would call what they do a "kit" vs "Scratch built". I bet most of us would go with the former. I also wonder how many people who don't own 3D printers (or do any cad designing) would think the opposite.
To me it doesn't really matter though. I enjoy the design process, probably more than the actual flying. And I'd be happy with whatever it would be "officially" counted as because I know I designed and built it. I'm just as thrilled when someone else builds my designs, btw.
If my RSO chose to argue the point I'd just say "Whatever dude, mark it how you want, I just want to fly the damn thing."