I’m in the process of re marking all of my tools and cases etc with u a uv pen. It won’t stop them from getting stolen but if they are recovered at least you can prove they’re yours . Apple tags or similar are also useful. Ultimately the best defence is to keep them with you where possible and try to avoid leaving them in your car or van . Cover them with sheets to keep out prying eyes, there are some very cheap and small alarms that will start screaming if they sense vibrations. In the end you can only make it as difficult as possible so force them to make as much noise as possible and light up the exterior with flood lights and cctv where possible.