3D printed vehicles and mechs I’ve been designing as a toy. Each unit is printed in series of separate pieces that have interchangeable joints so you can swap pieces such as weapons and armaments. 
do you intend to sell your designs? I am interested
Right now Im mainly focusing on two units and getting them made with injection molded plastic so I have a Kickstarter project.
While I am also offering the STL files for some units in the project, I haven’t actually considered selling designs as a standalone yet… maybe in the future though
Wow - absolutely fantastic! What are you printing with (machine/material)?
Do you do any post-processing before painting?
I use Makerbot Replicator 2x ABS at home and also I use Shapeways STL service to print in white plastic (usually after my Replicator gives me a good enough idea before I spend money><). Actually the Replicator 2x is not that far off but the main problem is the underside becomes so rough :(. Because they are assembled, each unit can be broken to simpler pieces to print.
For painting its better to have them primed first. For paints I just use Citadel Paints.
Excellent are you doing, I’m using PLA, what about ABS? Do you do the sanding and putty as well? Especially in Irons Legion.
And what kind of paint do you use?
For prototyping I use Citadel paints, mainly because most of their colors are already pretty suited for military industrial sort of look.
Though they are a bit simple color wise mainly because I needed it to be more consistent manufacturing wise (otherwise I would add more wear and tear sort of stuff).
What kind of paint is this? Maybe I could find the same type. And this time I’m using one car paint from Nippon Paint because it is easy to get.