i see colorado i'm in nor cal i would show you my tools that i used but there just junk
i just bought 16 gage sheet and made a cup from old brake drums
used round faced 3# hammer and worked
i'm no sheet metal worker but have a mentor
try and think in your mind that you want to push the sides in to the bottom of cup
don't beat to hard, go slow, then take a break and go slow
talk to blacksmith can help on line

I had a 56 TBird for over 20 years. Black with red interior and two tops, automatic with 312. First car I ever restored - did it in the late 70's. Had to sell it for kids college tuitions - still miss it.....glad Inline tube worked for you....Chris F100