As a test equipment designer, I have been involved in CAD software since 1989. (Before that, the drawing board (ugh☹️). We migrated from 3D wireframe to PTC's Pro Engineer solid modeling (parametric☹️☹️). Retired early in 1997 so for home use I bought a Russian made 2D CAD program (☹️☹️☹️).
Then I found a good basic 2D program called Autosketch😊 by Autodesk (Autocad). I have been using it for quit a long time for my model boat work. About 3 or 4 yeas ago I downloaded (free) Autodesk's 123D Design😊😊😊, a 3D modeling software program. It is real easy to use. At first I was sending my files to Shapeways for printing but now I have two 3D printers from QIDI and do most of my work in ABS which cements very well to styrene. I can also make a 2D drawing in Autosketch and export it into 123D Design and extrude (rotate, etc.) into a 3D item.
The first drawing is replacement thoughts for my Dusseldorf FLB2 superstructure I created in Autosketch. Here a scan of the kit plans is overlaid with my notes using Autosketch.
The second drawing is of my future (if I can get to it) towboat, the MV Arne Christiansen. This is page one of seven large pages detailing everything in 1/35 scale. (real boat:
https://www.cummins.com/case-studies/steiner-delivers-fourth-z-drive-pushboat ).
The third is is my current project, a WWII AMMO trailer using 123D Design and I am 3D printing this in 1/16 scale.
Lew