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.