This is a simple set of number stencils for labeling things like wooden crates with spray paint.
The individual stencils can be combined using the connectors. There is a simple connector for just joining the stencils in one direction and a “two way connector” to join the stencils in horizontal and vertical direction.
Also the “filler” parts can be used to cover the remaining holes if wanted.
The author marked this model as their own original creation.