I'm trying to recreate a part which has no drawing, no dxf files, only a SolidWorks part file which I can't even open the features for it and I'm quite unsure of the feature used here. I have tried using extrude from x, y, z plane to create the curved bulge part circled in the attached file. I've tried pasting a sketch onto a curved surface to extrude, which somewhat works but it does not merge with the main body. This part needs to be shelled from the inside for vacuum forming and since the part doesn't merge, it doesn't seem to shell. Any help would be appreciated in this matter. Thanks.