I made a manifold the quick and dirty way. 1" iron pipe, capped at both ends, drilled and tapped along the length. 1/4" pipe fittings. I avoided the seam. Sees 150 psi regularly, no problems after a year. A nice chunk of seamless pipe with a thicker wall would be perfect if you could scrounge it for free. Just not pretty, and probably not at all tolerant of side-loading the fittings.