I used to make bread cups by pressing the bread into the muffin tray. The bread cup is then used to fill with ingredients you like.
The disadvantage of the 'simpler' way is that there will be 'bread crease' and where there are creases, the bread will be thicker. What you need is have a few cuts on the bread and it will solve the problem.
Basically, you will need just a baking cup or muffin tray. To make things easier, I use an additional tool, a circle cookie cutter (actually, it my kids' play dough cutter. I 'stole' it from them :P). I used it to leave an impression on the bread, for 2 purposes. First, as a guide on where I should cut the bread and second to make it easier to press the bread into the baking cup. The impression on the bread makes it easier to fold and fit into the baking cup.
Please take note that the circle cutter have to be smaller than the inside of the baking cup, in order for it to work. The bigger the circle cutter is, the wider the bread cup will be.
Once the bread is fitted into the baking cup, toast it for 5 to 8 mins at 180C and the bread cup is really to be filled with your favourite fillings! If you are not re-toasting the bread cup after adding the fillings, You might want to toast it longer to get it slightly more brown. It's your preference.
I did two different bread cups with two different fillings here. The Egg Bread Cup is filled with chopped hard-boiled egg, topped with cheese and baked for 7mins. The bread cup has the corners trimmed-off. You can add mayonnaise to the chopped egg to turn it into egg mayo. My daughter doesn't want mayo. She wanted it to be toasted with cheese as the topping. Fussy kids, I have. :P
The Tuna Bread Cup has tuna in it (obviously). My son requested for it to be toasted, again, which resulted with the edges being more brown. I originally thought of just filling it with tuna without re-toasting. Hence, I had the bread cup toasted longer. But alas... Another point for you to take note for. :) Oh! The corners for the Tuna Bread Cup were left as it was, just to let you have another option.
Please refer to the slide show below for the steps on how I did the bread cup to get a better picture. Click on the photo to expand it for a clearer view.