What is the status of a non-cloth covering, such as putting your head on your watch?
the reason for leaning forward when saying tachnun is one should fall on one's face in shame for sins committed. the arizal held the hand was no enough of a cover and should use one's arm (not tefillin arm) however that one should not use one's bear flesh as one's arm cannot sufficiently be a cover for one's face when leaning forward. In my siddur it mentions a sleeve or tallis but that assumes one is wearing a talis and one isn't wearing a short sleeve shirt. according to many ideally one would be wearing a jacket during davening which would solve that problem but not everyone does, but then again neither does everyone hold like that arizal that the hand is not enough of a cover for tachnun. assuming though one is in the position of using one's forearm and having a short sleeve shirt it could be that one would be able to use anything to cover one's arm such as a paper towel. I don't think the watch would be a sufficient cover if the hand is not. While I haven't seen a source for it would there be any reason one couldn't rest your forehead on an object such as a chair or edge of a table in this situation?