Is the gap between the bricks the problem? If I were trying this I'd make a box form out of scrap with the outside of the wall on the bottom, pile the bricks in, sort them into whatever order you want then pour some kind of glue on top (which would be the inside of the wall). The glue would have to be thick enough that it doesn't puddle underneath the bricks. If you need it doublethick make two sheets and glue them back to back. I saw a video about a guy who builds huge models out of toothpicks and that's what he did, glued toothpicks together into giant sheets then formed the sheets into the shape he needed for the model.
That wouldn't make the gap though.