I’ve seen some that use a metal baffle where the beam hits a metal plate and is deflected to anther plate off angle Mounted in a metal box that captures beam reflections. Both plates have a heat sink and the whole thing was in a metal box. This was for a 25kw laser. The fire brick is usually all you need. For our usual power any brick is fine. I do however like the off angle deflection idea as it keeps the room dark. Bet a bullet stop box be rather good.