Here are some step-by-step images of the project so far.
The track housing for the Colossus was made using three Baneblades.
The main shape of the hull goes up next.
Added guns, these I replaced later on.
Size comparison with Angron.
I have started creating an interior for the commander control room. This area is split on two, divided by a shaft to bring shells up to the Doomsday Cannon. One side will be the Commander's office and the other will be a control room. I am waiting on pieces from Antenociti's Workshop to complete the control room.
Started adding the towers to the sides.
Started on the landing pad and building up around the Doomsday cannon. The top section, with the gun, comes off to give access to the control room and the landing pad comes off to allow access to the inside of the hull so that other items can be stored within it. I can fit all the other vehicles and artillery guns I have to use with my Squats/Demiurg.
Started detailing the Landing pad. You will note the mesh on the landing pad, the arch added to the doorway, ladders allowing access to the air defence platform. I also started detailing the front.
I replaced the guns because they were way too small.