Airvent thread

This is a thread for Airvents, to allow the window to close at 95%. Tested on the VW T5/6/6.1 Airvent that uses M5x6mmx7mm threaded inserts.

The file is .STEP, and I also included a really basic design of the insert, so feel free to modify it your Airvent uses different Metric.

You can find more information and the build process in:

https://wearebfree.com/blogs/bfreeblog/airvent-mod-how-to-close-the-van-window-completely