I needed a conical bottom tank to let my algae settle so I could drain it off.
I got a bucket, heat gun, pipe/ flanges, and clamps.
Basically heat up bucket why it's pivoting on flange and pipe. Then use pipe clamps to draw it out.
Step 1: Bucket Pivoting on Pipe
Mount your flange and pipe to a good surface so clamps can pull straight down from bucket.
Attach rope or wire to bucket.
Place larger heat resistant "die" to draw the soft bucket against.
Heat up bucket
Then evenly squeeZe the clamps to draw out the bottom.
Step 2: Finished Bottom
Here's the finished draw. I actually threaded the fitting on and used that to do a 2nd stage draw out of the bottom.
Don't drill a hole and then heat and draw or the hole will stretch and deform.
Step 3: Bulkhead Fitting
Here's the bulkhead fitting on bottom. Pretty useful.