How to make a bandsaw jig for these fence post caps

You don't need a jig

If you haven't learned the "trick" of supporting the workpiece using the cut off piece on the bottom, try it. You will always have a flat surface on the table even though you just made a curved cut. Make the cut and "reassemble" the pieces back together.

Can't you just start with a longer piece of the 4X4, mark out and cut the curve, rotate 90°, cut again, rotate, cut, until curved sides are complete, then do the same for the scallop, then cut the cap off. Or, if the caps are integral, just start with the full length post. Might be fun swinging an 8' post around, but should be doable.

I have a chop saw, i was thinking it would be easiest to chop up cap sections, lathe them for the inset grooved part, then, cut the points... I have 80 of these to do, so 80 8' posts would be a reall bugger.... and i cant find a lathe that big =)

I'm thinking band saw. If you're going to make them separate and fasten to the posts, cut a 4X4 twice the length of the cap, cut a scallop on each of the 4 sides, then cut the 4 curves for the point. Then cut in half. Looking at the picture, it doesn't look like the scallop is a turned groove, rather a scallop in each of the 4 sides.

I wish I have the idea. I wanted to make something like that too.