How to implement wall thickness Analysis for my .net project
If your talking about a hollow object, such as a cube with a hollow center. The wall thickness is determined by the model.

If your talking about a solid object, the wall thickness is determined by your nozzle diameter multiplied by your # of walls. This is all adjusted by your splicing software. If you have a nozzle of 0.5mm and you print at 3 perimeters, your wall should be 1.5mm. If you want the wall to be 2mm, then you will adjust your perimeters to 4. Everything within those walls will be whatever you choose for infill.

I work with ASP.NET, Windows Forms, and Console Apps myself. I'm sure you can find libraries capable of taking 3D models but I don't think it would matter because the printed thickness is determined by your splicing settings. 

Also for cost of printing, I recommend just using Cura which you just have to plug in some cost information about the filament and it will tell you estimated cost, mm of filament usage, and time.