Here’s the first day of working on the shell.
The basic process is pretty simple. I have about 10 yards of burlap fabric and some stucco mortar (not concrete!). I used a five gallon bucket to make some very soupy mortar, about as thin as pancake batter. I mixed some concrete color (a slate gray) into the mortar to eliminate the need for paint and to ensure that any cracks or flaking of the mortar–if any–wouldn’t be a lighter “concrete” color.
I cut the burlap into 4 x 36 inch strips. Wearing concrete-proof gloves, I dipped them in the mortar, swirled them around to coat them, then laid them over the frame. I overlapped the burlap strips and placed them at different angles (not all running the same direction) for extra strength.
I added extra mortar on top as I felt was needed–working to cover any burlap texture that showed through. Before it was dry, I used a trowel to remove any hand/finger prints from the surface.