This is so simple and obvious that I suspect most people would know it already, but for those that don't, here goes.
I had to make a dolly's high chair for granddaughter, but the principal is just as relevant for full size. The need was for four legs to splay evenly out from the centre at equal degrees. My drill press will adjust sideways but not forward, so I simply cut a piece of scrap timber the same size and shape as the bed of the drill press, and glued a strip of timber along one edge and another exactly the same on the under side on the side edge, if you can follow that. This meant that the material being drilled was tilted sideways and forward at the same angle. Drill two diametrically opposing corners and turn the guide over for the other two.
I hope I have made it clear, but really it's so simple I expect most will say, 'But of course!'
The collecting of facts is not the gaining of wisdom, or even knowledge; knowing that the earth is round does not prevent our falling off the edge of it.