This is a new tool that was added to UMM-USA’s line of modeling tools this fall. The tool consists of a thin double-edged saw blade and black plastic handle. It is intended to be used with resin parts and thin styrene.
The tool is used similar to a full-sized keyhole saw. While it can be used like a standard saw, cutting from the edge in, its principal use is to cut a hole inside a part. I experimented by drawing out a rectangular panel on scrap styrene, drilling pilot holes at each corner and then using the saw to cut from hole to hole, creating a rectangular opening. The corners were then cut out using a sharp Xacto knife.