The SOE tip is a good one.
But I'm generally not really a big fan of Add-ons for such arcane things as eaves.
For starters, you can do most of what you need within AC. And secondly, the more esoteric Add-ons aren't that well supported and tend to be buggy and may not be around 2 versions down the road (or even half a version down the road). Not a problem if you're doing a one-off project but hugely problematic if you're doing an ongoing refurbishment of an historical building (which is probably the only reason you'd need a specialized eaves Add-on anyway!!!)
I still have some duff Add-on called WindowMaker sitting on my shelf gathering dust. Appeared version 6.5 vanished version 7.0. That was a waste of US $200. Oh, and Abvents AV-Works. More money down the spout during version 8.1 only to purchase version 9 and realize Lightworks is way better. Another waste of US $200. RevealMaker - kind of useful but version 6 then whoosh, and curved wall reveals forbidden (nice to have an add-on dictate the geometry of your project), and about US $125. The only thing I seem to have missed is the Add-on called 'Useless Money Spunker V2.3'. Though I'm looking to spend US $500. if anyone has a copy.
That being said. For someone new to the programme, and dependent upon your needs, there are a couple of very useful Add-ons.
ArchiForma for free form modelling.
ArchiTerra for landscape and topography.
And ArchiStair seems promising, though it's relatively new and has a few things needing polishing. But the above are provided by Cigraph, who consistantly produce really useful stuff and timely updates, and!!!, they're very proactive about supporting their product.
Cheers,
Cameron Hestler, Architect
Archicad 27 / Mac Studio M1 Max - 32 GB / LG24" Monitors / 14.5 Sonoma