From an earlier post made by me in the help section.
It utilizes the same standard adapter collar that the drill press and the 565 cutting adapter use. That adapter gives a standard 1" tool diam that a 1" diam section of PVC pipe slips over and slides on just right.
Two wide slots are first cut down opposite sides of the upper end of the pipe as in fig 1. That creates two "ears". Radius the curves to eliminate stress points. The slots provide visibilty for the working bit. Holes are then drilled through those "ears" to allow for visibility on the sides. All edges are rounded, #3. Fine adjustment to the router cutting depth is provided via either a thumbscrew, #4, as in the 565 cutting adapter, or a threaded nut, #5.
The tool allows for freehand routing of signs, pumpkin/gourd carving to a specific depth, different art techniques, etc.