I modeled this digivice for a friend of mine as a prop for cosplay.
The ones from the photo are printed in ABS.
Use some spray filler, aceton vapor bath, or multiple layers of acryllic paint to get a clean and shiny surface.
Set the roof thickness to at least 1.50 mm to archieve a surface without bumps!
Higher infil ratio will help to get a better surface.
I used blender as the modeling software!
it is a free and open source program and is perfect if you cannot afford a licence for a professional Software.