I also used the LinkStage3 'save as directory' feature to make version control with git smoother. I really liked how this works, hopefully that feature makes it into master eventually.
Some highlights:
2004 phase 2:
This one was very informative. I ended up developing a workflow to make intersecting fillets doable using surfacing tools. One of the boolean operations for this model took multiple hours to compute
.2011 phase 2:
I like this one because it's a good demonstration of how well FreeCAD can do solid modelling. This model didn't require any hacky tricks to get good geometry. Dress up and thickness features just worked.
An aside about FEM:
the challenges usually have a mechanical simulation component. You're meant to use SolidWorks' simulation workflow for this, and then one one the challenge 'question answers' is the factor of safety of the part. Not knowing the exact material parameters or failure criteria that SW assumes for basic sims, I chose to just use this part of the challenge as FEM workbench practice. This was overall a good experience. I only managed to run out of RAM a few times
2022:
It's interesting to see the challenges get easier in recent years. Seems the approach to them has sort of changed from "here's a model with several features for you to figure out over ~0.5hour" to "you should be able to hack this out in a matter of a few minutes"
More images, just for fun:
