Well, for anyone still following this post:

The tank is finished for the most part..... I am kinda stuck on a plug
or lid for the top. I bought a 1-1/2 inch pipe plug to use but I am
having a difficult time finding a tap big enough for it...... I guess I
could order one, but that's about $30 for something I'll never use
again.

Construction is going very good...... As soon as I can decide what to
do about the plug/lid I'll weld the top on it and try out "da bomb"

Oh, 4 pounds of dry ice keeps only 2 days inside an Igloo cooler inside
your freezer.