These flexible wafers may be the best fit that I've tried. They seem comfortable and secure to hold about 1/2 lb (8 fl oz) or 300 ml.
The ileostomy fluid brings a pH level that makes sealing that stoma crucial.
About the first minute of adhesion needs constant, uniform pressure, and here's the tool for that.
This helps that seal last 3× longer. We apply heated uniform pressure against body around the stoma.
Heat the Tool with water
in a large coffee cup.