Small handle for holding 39mm wide razor blades. Can be used to help remove parts from the print bed or scrape off excess glue on the build platform (I normally prefer to use a sharpened Sizzix spatula but sometimes a razor blade more convenient).
The plastic should flex enough for the razor to be carefully inserted inside. Despite the pictures above, it's probably safer to print this in a bright visible color (silver and grey disappear too easily in a cluttered workspace).
The holes in the side are 6mm diameter and 4mm deep if you want to put a magnet in there.