Step 1: 55 gallon barrel
Step 2: Marking Door
Then I tried drilling small diameter holes in a row to make a slot in one corner to start the jig saw. I ended up snapping off the little drill bit so that ended that method.
I stepped back and thought about it and went and grabbed a BBQ lighter. I decided I'd try to heat up the blade until it would slide into the barrel. It worked like a charm. I didn't even have to get the blade red hot.
After I finished cutting the door out, I used the box knife to clean the rough edges.
Step 3: Cut the barrel in half
The barrel has several ribs so I just measured halfway between them and marked every so often.
Then I took some wide masking tape and wrapped it around the barrel to give myself a guide.
I heated the blade again and plunged it in. I rotated the barrel as I cut.
It cut great and both ends came out super square.