[Tim Hancock]

Lay pipe on bench or ground alongside a board or metal bar then use edge of bar to mark the whole length with a pencil to establish a straight parallel line. Mark your hole on each end and drill pilot holes with a very small drill bit being careful to keep centered on the marks. Then drill with correct size bit visually keeping bit straight. Or flip part over and make second marks exactly 180 degrees from first make. (one could also make a paper template to establish 180 degree by rolling and cutting a piece of paper to fit perfectly around tube, then fold paper in half to establish 1/2 circumference mark then put bac on tube and transfer the mark.

Lots of ways to do this simple task. Guys with lots of fab experience would simply do this satisfactorily in a minute or two by eye, but folks with less diy experience can use these other ways.