The rear brake hard lines

The rear hard lines are standard size with bubble (not double) flares. The simplest/cheapest way to get this, assuming you don't want to buy a flaring tool or stainless lines, is to remove the line as best you can - if you have to cut it mark the proper orientation that the parts line up - and bring it to your local auto parts store or euro repair shop. They can usually cut, bend and flare a custom tube for you for a reasonable price. VW dealerships are everywhere and they use the same size and style tubing, btw, so they'd have it.

Alteratively, get a bubble flare tool like this one and get some appropriate size tubing and fittings and make your own. That bubble flare tool is a really good price - I bought basically the same one about 10 years ago and paid $400. Still using it.