Propane tank build

[smokyvan]

This is my first thread and a way to introduce myself.
I love to cook and outdoor cooking is one of my passions.
Slowly I put together a small shop with woodworking and metal fabrication capabilities.
A few years ago I built my first "device", an argentinian grill.

I recently bought a used propane tank of about 55g that I would like to make into a side fire box smoker.
The tank is a domed cylinder (capsule?). I have a section of a pipe that I would like to use as a firebox.
Pipe and tank have the same diameter.
I used a calculator to find out all the dimensions that I need but I now face a challenge.
What's the best way to figure out the cutout shape for the intersection between the cooking chamber and the firebox?
I understand that it is more a metal fabrication question, but I was wondering if someone else had this problem before and could give a hand.

I was suggested to designing it in Fusion360 and generate a cutout paper pattern but I am almost 80 years old and that is a bit intimidating for me!

 

[kruizer]

Cut the domed part straight across at the height you want for the fire box and then cut the circumference to join the dome cut. Then put the fire box pipe into that cutout and mark with chalk to get your cut lines and then go to town

 

[smokyvan]

Cut the domed part straight across at the height you want for the fire box and then cut the circumference to join the dome cut. Then put the fire box pipe into that cutout and mark with chalk to get your cut lines and then go to town

I can visualize it for a square firebox, but I'm having a hard time with the pipe.

 

[pete mazz]

https://planetcalc.com/4580/

 

[smokyvan]

I'm still struggling with this...
Cut 1: cut the domed cilynder curve following the firebox pipe curve.
Cut 2: cut the domed cilynder bottom to catch the first cut and cut off the baseball shaped opening
Cut 3: insert the firebox pipe and cutout excess that protrude inside the dome