I'm dying to read what this project is. I delayed replying, so I could hone in on a specific tool to use. As it is, you could do the job with a hand or power planer, router (as was mentioned) table saw, radial arm saw (tilted 90 degrees for ripping and angled to whatever angle you want) or even a circular hand saw angled and using a rip fence.
I did carpentry and remodeling 25-30 years ago. Never did buy a power miter box, table saw or radial arm saw. I've built shelves and everything else like that using my portable hand saw. It can be pretty handy, in the right hands!
Seriously, I think the most versatile saw a do-it-yourselfer could buy, would be a radial arm saw. It can do the job of a table saw and power miter box, though it would be more clumsy than either. It's a compromise, but not a bad one.