Flexible wafers are the best fit that I've tried. A 'flex' type makes our physical activity much easier.
Attachment must be comfortable and secure to hold and carry about 10floz, or about 300ml, or about 1/2 lb.
Sealing against leakage with the flex type was tricky, and having an ileostomy makes that stoma seal crucial. The first minute of adhesion needs constant, uniform pressure, and moving fingers won't work well.
Here's a way to apply uniform pressure around the stoma.
That hex flange on this Tool helps get the job done.
Heat the Tool in a large coffee cup with hot water faucet, or microwave oven, and help that seal last 3× longer.
(I use faucet + microwave for just below boiling!)