I would suggest that you check the baggage in order to save you from any possible hassles. The railroad spike would most likely be declared prohibited, but being that it has trains attached to it and with it being more of a presentation, it could possibly be allowed. It would end up being left up to the discretion of the supervisor on duty. I don't know what airport you're leaving out of, but if it is a large one, check the bag so you wouldn't have to take the long walk all the way back to the ticket counter then go to the back of the security line again. Save yourself the hassle and check the bag. Have a good flight!