���I tried scarfing a bunch of Doug fir with a hand plane at first. I quickly bought a power plane and appreciated it very much. Making rails and spars with a circular saw looks ridiculously hard in hindsight now that I have a table saw. I still don't own a router, chop saw, or bench planer but they have crossed mind

Shinto rasp... one of those things made up of a buncha hacksaw blades, teeth on both sides. Bought one in '72 for building a stripper scow, still have it! Works great on epoxy for shaping & smoothing out drips & stuff.

Multi-tool! Corded or battery; mine's a corded Bosch I bought eight years ago for working with cedar siding. Finding it invaluable for sanding epoxy in cockpit of my current build, one of CLC's Waterlust canoes.  

riffler rasps:

https://www.clcboats.com/modules/catalog/product.php?category_qn=boat-building-supplies-epoxy-fiberglass-plywood&subcat_qn=booth-tools&code=riffler-rasp-set

Mighty handy little devils.

.....Michael

   About a decade ago I got a router, I forget what the project was, but it didn't get used much.  It was fabulous for trimming the deck on the Kaholo, cutting the deck plate hole, and installing the inlay.  

  Just recently I got a bit brace (old one off ebay).  The fine control you get compared with the power drill was really nice for drilling pilot holes for the deck plate and rigging (among lots of other ancillary projects like storage racks, etc.)

���Air conditioning.

   On the pricey side, a Festool orbital sander with a rectangular footprint. The ~3" width lets you run the sanders flat across panels, and built-in dust collection you can sand indoors. Downside was that once I'd laid out $800 for sander I 'justified' the cost by spreading it across more boats. Now there's no garage space and I'm going to fill up the lawn pretty soon.

 I'd like a workshop . . .

I wish that I had bought the Veritas Honing Guide and Lie Nielson Planes before my first build.  I struggled with dull, lower quality planes through all of my S&G builds.  The Robobevel is great fpor strip builders not using bead and cove strips, but some hand beveling is still required.  The Stanley Spoke Shave is garbage.

Double garage or barn.