In the top photo I have put thick slip to the base and to the form and assembled the two slabs. The jug supporting the standing slab is supported with a container of liquid, so it will not turn over easily. This will allow you to prepare the second slab and put it in place, as shown in the middle photo.
Note: For the large slabs I use my slab roller, but for the edge side and the base, I extrude a large coil (about 5") out of the pug mill and then cut it with a wire tool, producing 5-6" slabs.
The bottom photo shows my assembly of the edge of the form in place. You will note the clay is not all the way up the height of the form. By leaving it this way I can add whatever kind of top to the form that I find interesting, letting the same form actually become different images.
Continued in p.3.