I have been making delrin tops for my waterblocks for probably 2+ years now.
From all the consern about this and people asking, I finally made a batch of delrin WW tops that I am selling.
Dave, I made a pump housing for the c-systems pump and used it for some time, worked great. I mainly did it because metal barbs do not screw into your housings at all and I needed them in all the way for good looks
Jon