I've just added a template generator / calculator to blocklayer.com that will work out cutting angles to join 3 to 16 members radially in the centre, flat or on an angle.

https://www.blocklayer.com/center-join-templates.aspx

Enter member number, width, and angle of inclination and it generates a template to print at 100% printer scale, fold over the wood and mark or cut through.
Probably not the sort of thing you'd need very often, but if you do, it might come in handy?

If anything else needs to be added to it (or fixed), please let me know.

Join1.jpgJoin2.jpg