This is a control horn for RC airplane applications. The holes are sized for a 1.2mm control rod. The post that goes through the control surfaced is 5.5mm x 1.75mm and 15mm long. The post is ribbed so the locking part will grab onto it. I would still recommend gluing it down just for extra security, especially if using this on foam board. The length means it can go through most control surfaces with plenty of room to put the locking part on the back end. Any excess can be clipped off with your filament flush cutters.

This is patterned off of a commercial version you can get from Amazon. There is an example of the Amazon one (the white one) in one of the pictures. I modified it slightly to make it easy to print while keeping the flange fully intact. For convenience and organized storage, the locking part is attached to the horn like in a flat-pack card kit.

I've printed these in PLA and PETG so far. For me, the PLA worked better than the PETG. I'm sure it would work in ABS and ASA as well as any other filaments you might want to try. I recommend using one of your tuned profiles to insure good dimensional tolerance. Overextrusion makes it hard to assemble and can break the little tabs on the locking part. If that happens, you can still glue it all together and it will still work just fine.

The main picture shows it mounted on a Titan Dynamics Quail. I have yet to fly it, but it is a cool looking plane that I have high hopes for.

Enjoy!