The best DIY method is to use an arrow saw...
We got one for the club a year or so back and it sees a lot of use. We tell people now, "buy uncut shafts. We'll cut them to length for you, and get it right...". Not an obvious purchase for home equipment (the 'Best' one is nearly £200 now), but good if you have the cash. Pretty much a 'must buy' for a club, I would have thought.
I've seen plans for a Dremel based home brew saw, and I have (in desperation) cut shafts with a Dremel before (rigged up a jig from some bits of wood to keep the cuts square), but it's a nerve wracking business. A proper arrow saw makes it
so much quicker and less stressful.