For scratch building, a bandsaw is indespensible, and a scroll saw highly desirable. I use both, but I've about worn out my bandsaw and the scrollsaw is still fine. I use the bandsaw about 10X more than the scroll saw.

If you plan on building multiple quantities of anything, a router table (or two or three) is kinda the poor man's laser cutter. A cheap old B&D single speed router will cut most balsa/plywood OK...hardwoods are a different story.

A benchtop belt/spindle sander are handy