We have the example of the seals. Channellers were quite able to feel their evil and wrongness. We don't know for sure if this comes straight from the TP (though we know from Demandred the DO is struggling to break them and free himself) or from the Taint on saidin, but those are still objects that the OP "corrupted". The wrongness of the Shadowspawn is also TP-related and this too can be sensed. It sounds to me that to be sensed, the TP has to touch first something in Creation. There seems to be a "wrongness" effect to whatever the TP touches (the one exception we know of so far is the Chosen's Mark). It's the "source" and the weaves that cannot be sensed or seen by anyone but the one channeling them.

I don't think TP objects exist, personally. The dominant theme about the TP is that it corrupts, it doesn't create (I think it is in part due to the fact in order to create the TP would have to isolate its female and male halves, and instead it's pure chaos). It corrupts creatures, it corrupts flora, using it a lot makes a body rot. So far, we have no example of anything touched by the TP that doesn't rot/corrupts eventually.

Even for angreal/san'angreal, as I'm pretty much convinced they must be made with the two halves of the power, and what half is used for the "buffer" determines that it can be used only by the opposite gender. So I think angreal/san'angreal for the TP do not exist, while ter'angreal touched by the TP would get corrupted fast.

I don't think Mat's ter'angreal (and I don't rule out it's Finn made just because it's a OP object that Elayne could reproduce... let's remember those Finns were able to etch a OP-made blade with the inscription of their bargain with Mat (humans don't know how to do this - those blades are unalterable unless you use the OP), and they were able to alter that blade so that it could open a way out of Ghenji. This means they can create such "gateways" and we can't rule out they, not the AOL AS, made the two Doorway ter'angreal. It's pretty clear the Finns have advanced knowledge/technology and quite possibly have ways to use the OP. And I still have this hunch they're the ones who "knew the numbers of chaos" and long ago made the Portal Stones - RJ slipped in one of his answers and confirmed they have the ability to reach the "worlds of if".)