We'll go through the stove, piece by piece, to inspire you in your own designs.
The inner and outer cylinders each have a rectangle notched out of them. This is a good design, better than trying to intersect a circular tube through a cylindrical wall or anything like that.
There is a thick wall cylinder, a grate welded to the bottom, a loop in the center of the grate, and a stainless steel dish which is held by screws with spacers. Ash will fall down onto the dish.
The loop lets you pull the bowl out with an included metal hook. This makes it easy to clean out the ash.