Wow, using hypodermic needles, now to me, that’s thinking outside the box. I will have to say that when I was trying this combination, like you, it was before I figured out how to use two size ports. Do you use 2mm until the exit them use the needle? (any pics?) Also I have since found copper tubes, but they are coated silver. However, I’m not sure what will happen long term if the silver has a scratch or a cut tube(exposing copper) will do? They als have stainless but not as small as 20G needles. This is where the needles will be a much better choice. As far as putting together the rigs for measuring, the one for the impedance is pretty easy to do but since low pass xovers just don’t seem to work based on calculations, I don’t find it much useful. I don’t have very expensive equipment for my FR curve but with some luck, what I have works pretty well. I’ve used it to compare my Sure SE535s and SE846s and get curves very close to what I found online for those. I’ll try to post some pics when I get some together. Thanks for the input. I hope this link works Tubes: https://www.aliexpress.com/item/Bra...lgo_pvid=8db16d61-d95f-43ee-a56a-9daaa7151e23 It was with help from here but if I had to put my finger on 1 thing, it was getting light to the bottom. I have one of the small nail lights and what I do to accomplish this is turn the light upside down, put a piece of acrylic on top of the lights, set my mold on, place foil over entire bottom opening and cook. I used 40 seconds each way(right side up and upside down) pour out, repeat both for same times. Remove from mold, into glycerin and cook 4 min, move shell around and cook 4 more minutes all right side up, I have a small mirror under the rotating table(pics inserted later). Then place into isopropyl bath. Hope this helps.