These templates are for routing holes in decking so that a pull ring can be installed flush. I used these 50mm diameter pull rings. There's tons of different vendors selling them, and they look identical to those found on aliexpress. 

I used a 1/2" diameter straight router bit. A cheap Ryobi bit worked fine for the few holes I did. For bushings i used this 3/4" router bushing from this excellent design by @hoco. The bushings fit the Milwaukee M18 2723-20 palm router on the first print.  If you don't have a centering cone yet, I recommend this centering cone by @Vincent.

This is designed for Fiberon decking with a width of about 135mm. There is some minor variance between boards, so the template may fit tight on some and loose on others. This should fit on trex and timbertek boards as well. If it doesn't, you can use negative shapes in the slicer to remove the edges, or just print and smash them off with a hammer.

Trying this on a test piece first is recommended.

1. Use double sided tape to stick down the template. If you cut off the template edges, be sure to mark the template location with tape so you can line up the second template.

2. Route the circular template first with a depth that matches or is a bit less than the plate thickness (Pretty close to 1/8th inch). I've only done this with composite decking, so there is no grain to determine routing direction. If you're doing this with wood, you'll want to route clockwise (Double check me on that - i might be misremembering).

3. Remove the first template and test fit.

4. Stick down the key-stoned template over the circular hole you just cut. Pay attention to orientation here, this determines which way the ring pull will open.

5. Route through to the bottom of the board. I recommend several shallow passes using dust collection. Routing to the bottom of the board allows water to drain. Note the big divot is slightly off center.

6. Install pull ring. I recommend a center punch and drilling pilot holes.

7. Depending on the profile, the screws may poke through the back of the board. Cut them off if you're feeling fancy.