Here a device I designed long ago for getting perfect forty five degree edges in foam of any desired thickness.
I don't have mine any more because gave it away when I got the Proxxon hot wire cutter but the designs from those days I still have one.
I think that one may bring me to the other images and if so I'll add them here in a moment.
![Image](https://live.staticflickr.com/5819/21815110883_ddcd26e15f_c.jpg)
Daniel