Is it possible? Yes. And you've mentioned stability could be an issue. I'll add that if you count your time and wasted plastics to test the thickness, infill, etc. I think it'll cost more than just buying the extrusion.
That said, if you already have core xy printer, you can start testing by replacing the frame with a printed parts. Starts with the vertical ones.
This is okay. Been doing this for close to multiple decades now, my codes still are shit.
This is not, the thing is, once it works, it is one of the best feeling in existence. A very close second to the feeling after taking a huge dump.