how I can model the sides of this tank (the sides I marked by red)?
which tool I must use?
I try different tools but no good result.
Initially, you could use the top face of the cylinder, inset it a few times, turn on proportional editing and pull out the very centre poly, which would give you the bulge. Then use boolean to add the two sqaure sections.
Did a quick video, hope it’s of help:
https://youtu.be/2P6aAaZnCQ0
thanks.great help.
Glad it helped. 