Well some good news, we think that because the ring itself is mounted behind armor and has the single tooth mounted on it, we can make the ring out of a mild steel to make tapping it possible and reduce the price.

We can then get the tooth/blade made of hardox and bolt it to the ring with a few >M12 high tensile bolts.

The ring is mounted with 2 rows of skateboard wheels at 45° that run on the aluminium tracks bolted to the top and bottom of the ring. Using the skateboard wheels helps to prevent damage to the bearings, and they are really cheap. I will post a picture once I have modelled it.

We cannot decide what to use for the armor above/below the ring though, since it is angled we can't get it made of a large piece of hardox so the only really practical options are to either machine it out of a few pieces of aluminium (we can do this ourselves so keeps the price down) or get lots of small pieces of hardox cut and bolt them on to a frame underneath (more expensive but should be stronger).

Also bear in mind that it is invertible and we want it to be identically armoured both ways up.

The top/bottom flat armor is currently planned to be 4mm hardox with 4mm 6082T6 aluminium below it. (Might drop down to 10mm 7075 aluminium if its too heavy)