Here comes the third Gobsmasha. I'll have a nice squadron of three to bring the hurt on my opponents. I started with the shell, loosely based on a Leman Russ hull, don't forget to use gussets to keep the thing square:
Here it is in profile:
Rather than fight with trying to make the panel fit exactly I capped it to the end, but I've got a bit of bulldog going on here.
You could trim that down to make it flush, but I'd rather sand it smooth with a trusty emery board. There things are great for coarse work: