I have a model that was imported as an iges file. The original model needs to be extended. What I did was cut the middle section away and save as a new part. Then I went back to the original part and cut away the ends and did a save as for the middle part. Now I created an assembly where I imported the ends and placed them at their new location. Then I used extrude-boss to extend the end piece back to the middle section. Now I want to make this assembly a single model. I saved it as a sldprt, but a line shows where I attached the pieces back together. I wont this to be a solid part now. Anyone have an idea how I can do this.?