I got these heads used for next to nothing. The nice thing about the trammels is that you can make a circle from a few inches to 20+ feet, limited only by the length of the beam you clamp them to.

I use my router adapter often for cutting out speaker openings in baffle boards when building speaker cabinets. I circular groove down about 1/4", then rough cut the center out with a sabre saw, and then use a flush cut bit/bearing to clean up the rough sawn edge, using the side of the routed groove as the follower template.

It makes a perfect circle opening in just a few minutes.

I like the way you made the dovetail slide; it certainly is very satisfying every time you use your own self-fabricated tools.