For this sort of thing I'd definitely use modo in my workflow, because it's my 3D DCC of choice, though I'm certain Blender, 3DS, Maya or C4D would all do just as well (I prefer the artist-friendly workflows and the shader tree & nodal shading I get with modo) though I don't know that you can assume the client has 3D CAD files - for something like mattresses they may only have 2D CAD.
It'd be a trivial matter even then to extrude elements from their 2D files, and in my case in modo, instead of "cutting up" the resulting model to get a cross-section, I'd use a live Render Boolean or a live MeshFushion Boolean to get my section cut, so that I could, for example, animate the section cut to show the mattress being "extruded" in any video output, and/or in sheerly still output the client could direct where they want the section cut in realtime.
Surfacing the items to be photoreal is pretty simple these days, as most 3D DCCs support PBR materials; in some cases a client may prefer NPR (non-photo real) shaders - so cel shading and toon shaders to get an illustrative effect.
The other advantage to developing this in a real 3D DCC is that if later your client wants an animation showing the springs giving and recovering, the mattress layers squishing and expanding, you're halfway there if you develop your model well.