Importing CAD File Into Sketchup

I recently imported a 3ds file into Sketchup. However when I try to add material in jpg files into each of the different faces of the model, none of the faces will recognize and I am not able to individually color each piece of the model. Is there any way to add some sort of texture mapping so that each of the faces will recognize and I will be able to individually color each portion of the model?

You cannot add colour/textures to lines; you have to make them into faces/surfaces.

When you import, it just comes in as lines on a flat plane - you need to turn these lines into the edges of shapes before you can colour them in.

If you group surfaces, then a fill can be applied to that group as a whole (without having to do each surface individually) - every “default” fill within the group will be filled with that texture.

Given there are preexisting entities in the model space…
Upon import into SketchUp, the geometry of a CAD file is automatically made into a Component.
Entities within the context of a Component are isolated from the rest of the model.
Thus, you need to enter the editing context of the Component to work with the entities within it.

• Double-click on a Component to open its editing context.
• Single-click in empty space outside the component bounding box to close its editing context.

It sounds like you’ve applied materials to the Component from outside its editing context.
The result is, all default faces within the Component will display the material applied to the Component.

You’ll need to back up a bit to correct this. Simply apply the default material to the Component.
Then, open the Component for editing and apply your materials.

SketchUp’s 3DS importer supports faces.

3DS import options dialog box — SketchUp Help

If those advices dont work for you (reimport with faces, editing groups/components to paint directly into faces) can you answer this questions:

What tool exactly are you using to add materials to the model?

Are you dragging your images from a folder and into the model?

Are you using the paint bucket tool?