Use a Template for More Precise Cuts With Your Router
Routers are great tools, but they are unforgiving. Create a design template and use it to create precise and identical details every time.
Use a 1/4-inch piece of fiberboard as a template. Trace your shape on it and cut with a jigsaw or a small circular saw with very fine teeth. Sand the edges of the template to fit it, then attach it to the tree with double-sided tape.
You will need a flush cutter to shape your part, and a band saw can be useful for the first cut. Watch the full demo in the video above.
Creating a Pattern or Template Using a Router | WoodWorkWeb (YouTube)