Build process:
First, trim the 6" tube to length, and remove the end which is malformed from the casting process.
Here are the parts I had on hand, so will be modifying. Twist-lock cap and flange set, base, and fittings.
Assembly: I'll be brief here, as it's covered in many other threads, but I put Weldon #4 in the groove, let it sit for a minute, then slowly lower the tube in to the groove and let it dry. Gives a good clean bond, with no slop.
LEDs have not come in yet, it took two weeks to ship. I've gotten the test tube mounted in the flange lid, but didn't take a picture yet, will post again tomorrow.