This is a step by step breakdown of how I made one of the models on my Sketchfab. Some people might find the workflow I use interesting or informative. 

Finished Model

This is the finished model on Sketchfab:

Blockout

I started this model with a very rough blockout made in Maya - seen here in Zbrush: 

Hipoly Base

I then added detail to the blockout to create a base mesh for creating the hipoly from. Here you can see the mesh with extra loops for smoothing later. Some of the meshes are deliberately left in a fairly blocky state as I plan on detailing them in Zbrush in the next step. 

Detailing the Hipoly

I then added details to this mesh in Zbrush. I used polygroups and panel lines to create a lot of the seams on body of the lander which you can see me in the process of doing in this image. Later I would use custom insert meshes to add further small details. 

Lowpoly Model

I then created a lowpoly model using parts of the hipoly base as seen below

Texturing in Substance Painter

I then textured the model in substance painter after baking the hipoly onto the lowpoly. As you can see I've exploded the mesh into separate pieces to make baking and texturing easier. 

Here you can see that I have given the polygroups in Zbrush vertex colors to make masking the materials on the mesh much easier. Only a few of the details are hand painted. I avoid hand painting masks as it makes changes to the UV mapping or lowpoly topology harder to do later. 

The Final Model

And here is the final model again - this time in Unity.