I heard someone using 5/16ths brake line for the feed
I have personal experiance with using brake line, not on my VW turbo, but on a different turbo build. The brake line was cheap, fittings were fairly easy
to find, and it sealed up well.
The problem was that, in my instance, vibration caused the line to crack, right at the base of the flare. I tried putting a loop in the line to deal with it, but it just extended its life a little bit. Lasted a few weeks, but would always shake itself apart, and never at a good time

Eventually I went to the local hydrolic shop, told them what I needed and they made up a braided line with ends that I requested. IIRC it was like $35. The brake line was cheap, but it was alot of screwing around, and when it broke the first time, I almost buggered a turbo. .
And if you are using rubber lines for your drain / return, make sure they are silicone / some kind of oil resistant stuff, or at least of good quality. I tried that too, and used cheap heater hose. The hose swelled up after a few weeks and slid off. I cought it before I had any significant loss of oil, but it made a hellova mess of the engine bay, and the hose was hard to replace.
Just my .02