Adapter plate for a bike doll seat

The adapter plate is designed to allow a doll seat to be mounted on a bicycle rack. This is particularly helpful when a small child the seat post can not yet be extended far enough so that the doll seat can be mounted on this. On the bike in the pictures, the luggage rack itself is also in the way. 

I have printed the adapter plate with 100% infill in PETG so that it is as stable as possible. The layer height was 0.3 mm.

You can modify the plate according to your needs and bike with the OpenSCAD File.