Would you be interested in evaluating (or having your LLMs check out) my geometry kernel Aetheris for your project? I already have DSL (called Firmament) parser/lexer/AST part down, and it is designed to be easy to extend, so you don't have to write everything from scratch.

https://github.com/yuechen-li-dev/Aetheris

One of my goals when I built the kernel is I want to make building a pro grade CAD software as easy as wrapping a web frontend around the Aetheris libraries. It's still very much an aspirational goal though.

I love OpenSCAD and code-based CAD, but even I must admit it's really only good for simple things and is more of a toy than a tool to solve real world problems. The main issue is fundamental, which is that CSG operations change topology in unpredictable ways, and there is no reliable way to refer to the components of the result. This is already bad for a few operations, but becomes exponentially problematic for more complicated models. Even in 2D, suppose I want to make a C-shaped thing out of a box and subtracting a different box out of it. You don't know how many edges the result will have, or even how many connected components the result will have, so how do you go on to perform the next step "on that one part that I want" if it even exists? Of course for a single concrete instantiation this is not really a problem, but the whole point is to have the shape tunable based on parameters, and once you allow that all hell breaks loose.