To avoid the cracking happened last time, I covered the template made of wood with masking tape. In this way, the clay body can be separated easily from the wood board.
The work was built with slabs. I found this way suits me better, as I am not really good at coiling. I used smooth raku clay body, which is stronger and more forgiving. It can hold the structure even without other supports.
I made two mistakes during building; even they didn't cause serious problems at the moment. One happened when I tried to take out the wood. The result was the clay body cracked at the bottom edge. During the time, I was holding the bottom edge with one hand and trying to knock off the wood with another. So then the board came off, there weren't enough supports to hold it flat, which caused the clay body distorted and cracked. I should have waited the clay drier so I can turn the work over and hammer the board off on a foam. Or if the work close a bit more when I knocked off the board, it is less likely to distort. Anyway, I was too anxious. Sometimes more patience is needed.
The good thing is that the clay body was wet enough for me to fix it.
The other mistake was when I started to close the top. I closed too fast that there was a sudden slope that looked weird. I cut off part of the work I have built and redid it. Otherwise, the tank won't have enough depth when I turned it over, which means the setting for the inside may not fit in.
I didn't have sufficient time to redo a lot, so it came out with a small sphere on the top. It was what I planned, may not be ideal as well, but better than before.
I banished the surface when it was leather hard. By compressing the clay body, it can be more strong.
At the meantime, I did some tests about how to hang my other pieces in the air. I used fishing line since I want the works look like bubbles floating in the air. The more invisible line, the better.
For all the works I want to hang, I made a hole on them all the way through. In the first image, I used a button like acrylic, letting the line go through the acrylic's two holes, and then back to the top.
Then I found out that the acrylic was not necessary, so I tried the other way showed in the following image. For the work bigger and heavier, I made two holes to them. Two holes with four lines together should be able to hold the work.