If you've cut the acrylic using smaller stock, connect the two pieces with the 3D printed connectors and M2.5 screws.
Line up the laser mount's holes with the holes on the acrylic. Run the laser's wires through the bottom-left hole in the mount and the acrylic. This hole is larger on the acrylic.
Align the 3D printed mount's holes with the acrylic. Run the laser's wires through the larger hole of the 3D printed mount.