Ring target and magical item

[Ezechiel3571]

and none of it appears to be explicitly linked to a D: Ring. So it is simple to conclude, that a device effect just cannot have D: Ring, and be done with it.

I don't buy that. If Ring effect cannot be enchanted in item, it should be clearly stated in the rules, which is not the case. And I am not looking for D: Ring, but T: Ring. The duration is Sun.

It seems reasonable that if you want a T:Circle/D:Ring effect in an enchanted device, the device should trace the circle as part of invocation of the effect. Being the ring, of course, also qualifies.

That's sound reasonable and does not require any house rule.
The magic item holder must trace the perimeter of the Ring with the item at the same pace a mage would do. If there is no pre-existing ring, he must draw it - with adequate concentration roll (and in this case, unless specifically trained a grog would not be able since he would not know what symbols to draw), if there is a pre-existing ring he only need to trace the perimeter (and thus does not require to have any knowledge of magic).

Then again, this might be unbalancing, in that really large Circles/Rings are very powerful, and one of their limiting factors is indeed the risk inherent in tracing them. So, I'd probably require the user of the item to concentrate as if he were casting the actual spell.

It is a kind of follow up tothis discussion on Standing Stone. I could see that as a minor virtue the ability to create permanent and robust Ring, as well as to use them without having to draw them. You spend a season (or more) creating the Standing Stone (probably a MuVi effect) enabling user with the right virtue to use is for their Ring base spells.