Coming off a several-year hiatus from Prototyp with a resolve to move to a CAD (Metasequoia for now) and Pepakura development process. This leaves me with a bit of a learning curve to scale before I can get back to designing cars. I found some Metasequoia tutorials for model planes that have helped me get my head around the concepts involved in creating a cad model from scratch.
My scale technical four-view drawings from Illustrator are placed as backgrounds to trace over with 3d forms in Meta. It's unfortunate that there's no way to use the technical vector data directly as a basis to extrude forms as this would make working in Meta that much faster and more precise. There is also some wackyness concerning scale going from an output from Illustrator, to those images placed in Meta (at what appears to be low-resolution), to Meta's arbitrary "units" based grid, then onward into Pepa which has its own 'finished size' panel... With some ratios worked out across the three apps, the output is pretty much exactly 1/24. I won't know for sure until I try to splice some new CAD work onto current hand-projected projects.
All that said, progress is good, I think. The first project I've given myself is to tackle the somewhat simply-formed BMW LMR which won Le Mans in 1999. First-round CAD roughing is looking good, I'm scaling the steep part of the learning curve quickly. The advice I have is to get the most form out of the least number of slices. I have to do this in addition to maintaining shapes which can plausibly be replicated in paper.
The next big mystery is how much work I will have to do "post-Pepa" versus what comes "for free" in Pepakura with regards to tabs and slots and articulating panel divisions...