Having a jig as above would perfect the angle part. Thing there will likely come down to ? Need 3 holes? Then something like Ducky points to I have the Rockler version, with the tilting base, but it was an expenditure. That makes cutting pipe, and drilling holes, and welding together something like Ryan talks about as the best jig.
For the simple version setting it in a V, clamping it strong as you can, and using an angle gauge held up as a visual guide, and go for it. Most of the chair makers I have met, do this for the rake on chair legs, so it can work on special needs work.
Search Miter finder gauge, protractor, angle finder gauge, many of them out there from very cheap, to pretty expensive.
