im making my 3v setup now, HLT has a Vinyl Sight Glass made for it, I'm positive it wont add and flavour as there would be stuff all water in conact with it that ends up in the brew... plus its only going to be used until i get a bigger brew pot then my old one will become the HLT and i'll get a proper sightglass from GG
Same stick idea for kettle, wouldnt want to risk anything other than my Tap in it as i know with the 2 x 15mm SS washers either side of it and silicone bakeware gaskets.... its not moving nor leaking....
Just working out what kind of hose to use for transfers between HLT-Mashtun Mashtun-Kettle Kettle-Cube
Edit--
I stretched my Vinyl tube over a poly barb that it had no chance of going over by using the missus Steam Mop the the steamer attachemnt, stretched it with pointy nose pliers and steamed the hell out of it, got it just on the barb, then steamed through the barb and used gloves to Push it on tight..... its going NO WHERE and then i put a Cable tie on it to make sure