Wee! I’m pleasantly surprised that your interested in OpenSCAD. You can get a taste for the language and judge it’s size with this cheat sheet and get more details when needed from the manual. It’s a pretty small language and lacks some of the primitives you’d get with another program but you can generally make or find missing things. I looked up the formula for Bezier curves and a couple of functions later I could generate a list of points to make a polygon for example.
I need to get busy and try out those addons for Blender. It really is a great program. It started as an in house solution and then the creator gave it to the world for free. Now it’s a great example of what OpenSource can achieve. It’s almost unrecognizable compared to what it was when I first discovered it. Knowing some people that use it could give you a leg up if you go that route.
EDIT: @Mohjo I forgot to mention that I made an OpenSCAD program to make metric nuts and bolts. It may not be the cleanest code but it works well enough and demonstrates some of what can be done.
EDIT2: @Mohjo You mentioned giving Inkscape a look and while I have and like it, I’m not sure it’s the right tool for parametric work. I could be wrong on that as I don’t use it often. Might be worth checking out LibreCAD (free and open source) for 2D which is what qCAD was forked from.