The parts are flimsy and the places that join don't have sufficient surface areas to make a good friction fit, so all mine are glued together using airplane glue, or whatever they call it these days. A derailment and collision will send the parts flying all over the ROW. If you plan to install signal heads that have any significant mass at all, you'd be better off gluing. It's not as though they are rare or valuable. I bought a dozen or so of them, used, a few years ago for 5 bucks.