I made this jig a few years ago when making a manifold for my YB Cosworth.

It was sized for 1.5" schedule 40 pipe but could easily be adapted to take slightly bigger or smaller diameter/wall thickness.

Allows plenty adjustment for angle.

Photo shows the jig next to a standard A4 sheet of paper for size comparison. I used this in a band saw and it is very sturdy when clamped down. Much safer and more robust than using a plastic 3D printed jig in my opinion and this allows for adjustment of angle rather than having a bunch of fixed angle jigs.

Photos show the manifold I made with this jig being used for the collector section.

Any questions please ask