This is a design for twin motor mounts that allow you to mount 1306 sized brushless motor to the wings of a Lidl glider aircraft. It may well fit other aircraft.
The design calls for two small slots to be cut in the underside of the aircraft's wing which the motor mounts slot in to. Contact adhesive glue can be used on the flat side of the motor mount against the wing, hot glue could be used to reinforce the leading edge a little and tape could be run over the motor mount once in place. I expect this to be enough for small motors.
There are two files that are mirror images of each other. A small amount of tilt (5 degrees) is built in to each motor mount to account for the wing sweep angle on the Lidl glider so that the motors point directly forwards.
There is a square cut out in the motor mount that's correctly sized for 10 amp X-Rotor ESCs and probably other small ESCs too. The channels in the motor mount are to allow the wires to run neatly.