An in vitro testing process for simulating conditions of a stomach, comprising, in combination: providing an intragastric device to an acetone bath； inducing swelling of the intragastric device； exacerbating weak spots in the intragastric device； observing the results； and estimating the results of an in vivo study. Improvements to an intragastric space filler to reduce failure at a balloon to shaft area including an adhesive fillet, washers, a balloon cuff and collar, a molded in balloon fillet, and a one-piece molded balloon assembly.
