Once the rubbing establishes the edges clearly, it is then firmly applied to a photo with the correct colours/content by using scotch tape. Following the lines (with scissors or knife) on the rubbing is easy, even with very small pieces.

Then, with a small brush, generously apply the gloss medium (which I use instead of glue) and work the cut-out into place. Gently put pressure onto the sliver of colour to get the medium out from underneath and spread it around so that no globs of it will be evident after drying.