I've tried to 3d print this at home, many times. the layer adhesion was the issue i struggled with for long term use. it worked fine for a couple days but the repeated tightening and undoing started to crack my home printed part. Due to this, I decided to just have one made for me using my 3d model! inner diameter of the cap is 38 mm and the outer edge is 70 mm which is where the sealing actually happens. the model does not include the gasket which has a height/ depth of 2mm (I just printed my gasket out of 95A TPU) i will have the files for cap and gasket posted on cults3D. just search BMW G650 XCOUNTRY and it should come up. thanks! safe riding!