Thanks for the interest Bruce! The part has been purged of course. With such thin material you never want to take the risk of not purging. I just made an aluminum box for that with a big hole for the part to slip in until it hits the flange (the walls go down more under the flange, it's just not visible in this picture). It is then secured with an aluminum flange that slides on from the top. On the other side I just tape it. Harder to explain than actually doing it 😅 it's quite simple and works great, keeping the flange flat as well after welding.