I’m cautious with laser cutting PC, especially for this context. You can laser-cut 4 mm PC, but the heat input leaves residual stress that’s more prone to crazing and cracking. Laser edges can look fantastic, almost “flame polished”, but that’s exactly the sign you’ve melted/reflowed the edge. It’s especially bad if there’s any chemical/solvent exposure or cyclic vibration. Generally, routing is the safer default. Routing with a sharp O-flute and good fixturing gives you a cooler cut and lower stress. Internal radii are limited by tool diameter, so plan radii around that.

Waterjet is also a good option for PC in that thickness. You can get a slightly frosted edge and taper if the shop isn’t careful about multi-axis compensation. Also, watch fixturing – thin plastics can flutter. If you must laser: use the right wavelength/system (some lasers behave better than others), avoid ultra-tight radii, keep holes away from edges, and consider annealing after cutting to relax stresses. Also, use shoulder washers or grommets and don’t over-torque fasteners. But for bolted safety panels with vibration, I’d default to routing (or waterjet if routing geometry is awkward) and treat laser as a last resort unless you can validate with stress/chemical exposure testing.