I found that the first basic requirement is a parallelogram as the foundation of the unit. Then you anchor one of the extended ends to the table, the other end holds the "tracer", and the tool is mounted on one side of the parallelogram. Next, and after a lot of trial and error, I realized that the three points (anchor, tracer, and tool) must be fixed so that they are always in a straight line. This keeps the finished work from leaning to one side or the other, or being skew. Finally I began to understand that the measurements for the sides of the parallelogram and the distance from the parallelogram to the anchor and the tracer are the controls for the scale of the finished work compared to the original.
I even made a pencil holder and mounted it on one side. This assembly is held together by one inch bolts and nuts.
I used my logo and traced it to see what my efforts might uncover as problems.
The tool is my DREMEL Multi Pro, 2 speed, Model 285 Type 5. I removed the cap on the base of the tool and measured the diameter of the threaded area, which is 3/4".
Once the tool is inserted and the cap screwed back on, it will guarantee that the tool will not slip and possibly change the depth of the cut. The lines drawn from end to end and the lines perpendicular to that are the guides for the placement of the metal piece that also has lines indicating the center of the hole.
I aligned this mark with each line on bottom and top that goes end to end.
I cut the spacers 2 1/2" wide and 4" wide and placed the card stock on top of one end. This showed me how each of the spacers had to be shaped before I put the pieces together.