Hi, i needed a dwg to step converted and did some claude-ing for fun, to see if it's possible, and with old Opus versions i got a preliminary POC, where it would open the models but geometry was pretty bad, but with Fable and now Opus 5.5, i pretty much believe this is better than most converters i've tested. logically i then also converted it to a free web viewer (reads a bunch of formats but was thoroughly tested on DWGs and some steps).

https://cadyon.com/viewer/

The details were ironed out by vibe explaining to the AI what's wrong on the corpus of some 3.5k 3d files I had, so for that set everything is correct visually, and outside it, it's probably not perfect but that's why the test version is out, and converter itself is pretty cheap (200 eur, no subscription). I've also resolved special cases like blocks, nested blocks, colors in dwg etc, i think it's pretty polished for a 1 man project with AI. If you use cad like STEP and DWG formats often, please try the viewer, i genuinely think it's pretty usefull. also available as PWA and it has a bunch of cool features. And btw binary decoding was done in "clean room" as in i specifically instructed claude not to search web or decompile anything, it was purely done by comparing DWG ACIS exports with raw DWG's.