Here's a pic of the same cement block that is covered in thin-set is now further covered in Geopolymer (GP). The big test is which trowel notch size provides the best adhesion. I will go with the smallest notch size with good adhesion. This will provide the most efficient use of materials.
Here's a pic of the 1st layer of the permanent Bell. It is nearly complete. I need to fill the remaining blocks with Cob to finish it. The frame of the DSR is shown to show where it will fit. However, it will be located on top of the 4th layer.